Anyone have a report change from one AMC to another? Same client. At what point is it a new assignment requiring a new site inspection?

It's got the same client (slightly different address) and I've had the same contacts from the beginning of the assignment until now. Both AMCs are underneath the ownership of one company since the yaquired the other one last year, but both AMC license numbers are still active with my state.

At the beginning of the assignment, I had an engagement letter that gave instructions including to stop working on the report and contact the AMC if I saw XYZ. When I saw XYZ, they told me to send them a statement. I sent it and they paid me my trip fee (a generous amount actually, without my request).

I later on get contact from some of the same people asking me about my availability and how much I would want to complete the assignment. We have some back and forth and after I get them to confirm that this is a continuation of the original assignment, and not a new different one, They set me up with a link. I notice that it's the subsidiary AMC now. That's probably not a big deal. I notice that the engagement letter on the new portal isn't exactly like the original one. it's probably mostly the same with a little different format though.

I think I can send them the original engagement letter and just list out some of the basic changes that the requirements have been updated to (like the new AMC), and get them to agree in text that the original engagement letter will be the scope of work that I'm developing from.

maybe I'm thinking about this too much. What else should I get in writing to make sure this is legally the same continuation of the original assignment?