How can we submit a PSL order with Exit order not the same quantity?

Problem

I cannot use Brackets, OCO or OTO for the case below:

I have a open position with quatity 2.
Then I want to submit an exit order with quantity 1 and PSL quantity 2.
If the exit order is filled, the PSL with quantity 2 is canceled, and a PSL quantity 1 should be submitted.
There is no API support that case.

I’m using the paper trading.