Transfer worksheet can not transfer to the same Customer and transfer a part of item amount?

1^st step: I choose Customer ID from

2^nd step: When I want to choose Customer to is the same as Customer from, the system didn’t allow and show a message like below printed screen.

In this case I want to transfer to the same customer but different Dist ID => I think it’s reasonable bussiness process in real.

3^rd step: When I want to transfer a part of Item amount but the system didn’t allow me and showed a message like below => I have only one way to transfer a part of Item is Split that item first then transferring it?