Conditionally block field update with block / unblock flow steps

Today, we can block field updates based on source. But we would need to be able to do the same thing only in certain records.

Originally, this idea was about having 2 choices for each field and each source:

• Block always (currently available)
• Block if member of smart list, to be specified by the admin.

But @Sanford Whiteman​ made good point re. performance issues and proposed a much better solution (see below): having a "Block field update" and "Unblock field update" flow steps that would do the job for each lead. The flow steps would have 2 parameters :

• Field name (with the capacity to select multiple fields)
• Source (with the capacity to select multiple sources)

Use case:

• Make sure that certain contacts from the CRM would not have their key information updated by a Marketo form, a field update not a Change Data Value
• Make sure that some records that are sync'ed by a third party software through API could have their sync UID blocked from any update, only when they are of a certain type...

-Greg