If I had FEED documents requiring any given specific order of build or process of constructing, I would not approve an RFR without putting the FEED engineers in the loop. Especially one like this.
It is almost like a game to some contractors now, to read the FEED, understand that it will take more time, and bid it on the lesser time anyway.
When it comes time to build, they wait until they have schedule pressure on their side, then hit the owner with a request for relief and a sad tale about how ridiculous and onerous a given requirement is.
This leaves the owner exposed. Those FEED documents are typically what they received their initial approval from (governmental, corporate, etc). It's not a good idea to be changing them on your own.
I strongly advise you to send this to your FEED engineers before approving.