Hello,
Change to Partner functions after Invoice is saved is not allowed.
What you can do is have a Z-table with invoice number and Partner functions. For the Invoice where the sub Dealer is not available at time of creation, some end users can be given Authorizations to maintain this Z-Table.
Another option could be to automate the update of this Z-table by allowing users to enter the Sub Dealer Partner number in one of the Invoice Texts and then a batch program can update the Z-Table or other way around.
Thanks,
Jignesh Mehta