In v16 the behavior has changed when returning from a child in a multi file solution and gives a 301 error when editing the portal.
In the gtrr perform script a field in the portal is updated. Back in the parent a commit is used to finish the master script. If I try to update a record in the portal an error shows "you cannot change data because you are in the same record in another window."
This "feature enhancement" does not happen in FMP15. To "fix it" in 16 I have to add a commit at the end of the child script.