diff --git a/api/api_full.go b/api/api_full.go
index fb1810ad9..6ff5b0709 100644
--- a/api/api_full.go
+++ b/api/api_full.go
@@ -403,17 +403,29 @@ type FullNode interface {
 	// It takes the following params: <multisig address>, <proposed message ID>, <recipient address>, <value to transfer>,
 	// <sender address of the cancel msg>, <method to call in the proposed message>, <params to include in the proposed message>
 	MsigCancel(context.Context, address.Address, uint64, address.Address, types.BigInt, address.Address, uint64, []byte) (cid.Cid, error)
+	// MsigAddPropose proposes adding a signer in the multisig
+	// It takes the following params: <multisig address>, <sender address of the propose msg>,
+	// <new signer>, <whether the number of required signers should be increased>
+	MsigAddPropose(context.Context, address.Address, address.Address, address.Address, bool) (cid.Cid, error)
+	// MsigAddApprove approves a previously proposed AddSigner message
+	// It takes the following params: <multisig address>, <sender address of the approve msg>, <proposed message ID>,
+	// <proposer address>, <new signer>, <whether the number of required signers should be increased>
+	MsigAddApprove(context.Context, address.Address, address.Address, uint64, address.Address, address.Address, bool) (cid.Cid, error)
+	// MsigAddCancel cancels a previously proposed AddSigner message
+	// It takes the following params: <multisig address>, <sender address of the cancel msg>, <proposed message ID>,
+	// <new signer>, <whether the number of required signers should be increased>
+	MsigAddCancel(context.Context, address.Address, address.Address, uint64, address.Address, bool) (cid.Cid, error)
 	// MsigSwapPropose proposes swapping 2 signers in the multisig
 	// It takes the following params: <multisig address>, <sender address of the propose msg>,
-	// <old signer> <new signer>
+	// <old signer>, <new signer>
 	MsigSwapPropose(context.Context, address.Address, address.Address, address.Address, address.Address) (cid.Cid, error)
 	// MsigSwapApprove approves a previously proposed SwapSigner
 	// It takes the following params: <multisig address>, <sender address of the approve msg>, <proposed message ID>,
-	// <proposer address>, <old signer> <new signer>
+	// <proposer address>, <old signer>, <new signer>
 	MsigSwapApprove(context.Context, address.Address, address.Address, uint64, address.Address, address.Address, address.Address) (cid.Cid, error)
 	// MsigSwapCancel cancels a previously proposed SwapSigner message
 	// It takes the following params: <multisig address>, <sender address of the cancel msg>, <proposed message ID>,
-	// <old signer> <new signer>
+	// <old signer>, <new signer>
 	MsigSwapCancel(context.Context, address.Address, address.Address, uint64, address.Address, address.Address) (cid.Cid, error)
 
 	MarketEnsureAvailable(context.Context, address.Address, address.Address, types.BigInt) (cid.Cid, error)
diff --git a/api/apistruct/struct.go b/api/apistruct/struct.go
index de0ddd31b..2325ae93a 100644
--- a/api/apistruct/struct.go
+++ b/api/apistruct/struct.go
@@ -202,6 +202,9 @@ type FullNodeStruct struct {
 		MsigPropose             func(context.Context, address.Address, address.Address, types.BigInt, address.Address, uint64, []byte) (cid.Cid, error)                          `perm:"sign"`
 		MsigApprove             func(context.Context, address.Address, uint64, address.Address, address.Address, types.BigInt, address.Address, uint64, []byte) (cid.Cid, error) `perm:"sign"`
 		MsigCancel              func(context.Context, address.Address, uint64, address.Address, types.BigInt, address.Address, uint64, []byte) (cid.Cid, error)                  `perm:"sign"`
+		MsigAddPropose          func(context.Context, address.Address, address.Address, address.Address, bool) (cid.Cid, error)                                                  `perm:"sign"`
+		MsigAddApprove          func(context.Context, address.Address, address.Address, uint64, address.Address, address.Address, bool) (cid.Cid, error)                         `perm:"sign"`
+		MsigAddCancel           func(context.Context, address.Address, address.Address, uint64, address.Address, bool) (cid.Cid, error)                                          `perm:"sign"`
 		MsigSwapPropose         func(context.Context, address.Address, address.Address, address.Address, address.Address) (cid.Cid, error)                                       `perm:"sign"`
 		MsigSwapApprove         func(context.Context, address.Address, address.Address, uint64, address.Address, address.Address, address.Address) (cid.Cid, error)              `perm:"sign"`
 		MsigSwapCancel          func(context.Context, address.Address, address.Address, uint64, address.Address, address.Address) (cid.Cid, error)                               `perm:"sign"`
@@ -887,6 +890,18 @@ func (c *FullNodeStruct) MsigCancel(ctx context.Context, msig address.Address, t
 	return c.Internal.MsigCancel(ctx, msig, txID, to, amt, src, method, params)
 }
 
+func (c *FullNodeStruct) MsigAddPropose(ctx context.Context, msig address.Address, src address.Address, newAdd address.Address, inc bool) (cid.Cid, error) {
+	return c.Internal.MsigAddPropose(ctx, msig, src, newAdd, inc)
+}
+
+func (c *FullNodeStruct) MsigAddApprove(ctx context.Context, msig address.Address, src address.Address, txID uint64, proposer address.Address, newAdd address.Address, inc bool) (cid.Cid, error) {
+	return c.Internal.MsigAddApprove(ctx, msig, src, txID, proposer, newAdd, inc)
+}
+
+func (c *FullNodeStruct) MsigAddCancel(ctx context.Context, msig address.Address, src address.Address, txID uint64, newAdd address.Address, inc bool) (cid.Cid, error) {
+	return c.Internal.MsigAddCancel(ctx, msig, src, txID, newAdd, inc)
+}
+
 func (c *FullNodeStruct) MsigSwapPropose(ctx context.Context, msig address.Address, src address.Address, oldAdd address.Address, newAdd address.Address) (cid.Cid, error) {
 	return c.Internal.MsigSwapPropose(ctx, msig, src, oldAdd, newAdd)
 }
diff --git a/node/impl/full/multisig.go b/node/impl/full/multisig.go
index f1e3c61fd..9f412aa07 100644
--- a/node/impl/full/multisig.go
+++ b/node/impl/full/multisig.go
@@ -130,6 +130,33 @@ func (a *MsigAPI) MsigPropose(ctx context.Context, msig address.Address, to addr
 	return smsg.Cid(), nil
 }
 
+func (a *MsigAPI) MsigAddPropose(ctx context.Context, msig address.Address, src address.Address, newAdd address.Address, inc bool) (cid.Cid, error) {
+	enc, actErr := serializeAddParams(newAdd, inc)
+	if actErr != nil {
+		return cid.Undef, actErr
+	}
+
+	return a.MsigPropose(ctx, msig, msig, big.Zero(), src, uint64(builtin.MethodsMultisig.AddSigner), enc)
+}
+
+func (a *MsigAPI) MsigAddApprove(ctx context.Context, msig address.Address, src address.Address, txID uint64, proposer address.Address, newAdd address.Address, inc bool) (cid.Cid, error) {
+	enc, actErr := serializeAddParams(newAdd, inc)
+	if actErr != nil {
+		return cid.Undef, actErr
+	}
+
+	return a.MsigApprove(ctx, msig, txID, proposer, msig, big.Zero(), src, uint64(builtin.MethodsMultisig.AddSigner), enc)
+}
+
+func (a *MsigAPI) MsigAddCancel(ctx context.Context, msig address.Address, src address.Address, txID uint64, newAdd address.Address, inc bool) (cid.Cid, error) {
+	enc, actErr := serializeAddParams(newAdd, inc)
+	if actErr != nil {
+		return cid.Undef, actErr
+	}
+
+	return a.MsigCancel(ctx, msig, txID, msig, big.Zero(), src, uint64(builtin.MethodsMultisig.AddSigner), enc)
+}
+
 func (a *MsigAPI) MsigSwapPropose(ctx context.Context, msig address.Address, src address.Address, oldAdd address.Address, newAdd address.Address) (cid.Cid, error) {
 	enc, actErr := serializeSwapParams(oldAdd, newAdd)
 	if actErr != nil {
@@ -244,6 +271,18 @@ func (a *MsigAPI) msigApproveOrCancel(ctx context.Context, operation api.MsigPro
 	return smsg.Cid(), nil
 }
 
+func serializeAddParams(new address.Address, inc bool) ([]byte, error) {
+	enc, actErr := actors.SerializeParams(&samsig.AddSignerParams{
+		Signer:   new,
+		Increase: inc,
+	})
+	if actErr != nil {
+		return nil, actErr
+	}
+
+	return enc, nil
+}
+
 func serializeSwapParams(old address.Address, new address.Address) ([]byte, error) {
 	enc, actErr := actors.SerializeParams(&samsig.SwapSignerParams{
 		From: old,