update Compatibility section

Author: hugohn

bip-hugonguyen-bsms.mediawiki

@@ -69,7 +69,7 @@ The Signer is any software or hardware that controls the private keys and can si
 
 * The Coordinator creates a new multisig wallet creation session. The Coordinator constructs the multisig script and its policy parameters, such as the required number of signatures and the total number of Signers (<tt>M</tt> and <tt>N</tt>).
 * The session should expire after some time period determined by the Coordinator, e.g., 24 hours. The timeout allows the encryption key to have lower entropy.
-* If encryption is enabled, the Coordinator distributes a secret <tt>TOKEN</tt> to each Signer over a secure channel. The Signer can use the <tt>TOKEN</tt> to derive an <tt>ENCRYPTION_KEY</tt>. Refer to the Encryption section below for details on the <tt>TOKEN</tt>, the key derivation function and the encryption scheme. Depending on the use case, the Coordinator can decide whether to share one common <tt>TOKEN</tt> for all Signers, or to have one per Signer.
+* If encryption is enabled, the Coordinator distributes a secret <tt>TOKEN</tt> to each Signer over a secure channel. The Signer can use the <tt>TOKEN</tt> to derive an <tt>ENCRYPTION_KEY</tt>. Refer to the [[#Encryption]] section below for details on the <tt>TOKEN</tt>, the key derivation function and the encryption scheme. Depending on the use case, the Coordinator can decide whether to share one common <tt>TOKEN</tt> for all Signers, or to have one per Signer.
 * If encryption is disabled, the <tt>TOKEN</tt> is set to <tt>0x00</tt>, and all the encryption/decryption steps below can be skipped.
 
 =====Signer=====
@@ -185,9 +185,13 @@ For signers that use QR codes to transmit data, key and descriptor records can b
 Also refer to [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-015-account.md UR Type Definition for BIP44 Accounts] and [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-010-output-desc.md UR Type Definition for Bitcoin Output Descriptors] for more details.
 
 ==Compatibility==
-To comply with this standard, a Signer must be able to persist the descriptor record in its storage. 
+BSMS is opt-in, meaning existing multisig wallets can continue working as-is, with the caveat that current multisig solutions are full of pitfalls. Some of the problems have been described in the [[#Motivation]] section.
 
-Existing multisig wallets should delay upgrading to the BSMS scheme until all participating Signers have added support for BSMS.
+To comply with this standard, a Signer must be able to persist the descriptor record in its storage.
+
+Once a Signer has implemented BSMS, the user can create new multisig wallets using BSMS or migrate existing ones to BSMS.
+
+Existing multisig wallets should delay upgrading to BSMS until all participating Signers have implemented BSMS.
 
 ==Security==