I believe regular withholding would need to be remitted to the tax agencies under the beneficiaries SSNs for them to get credit on their own returns....you cant do it with just the 1041 and the K-1s like you can with backup withholding or estimated payments..

I found this in a quick google search

https://www.taxcpe.com/blogs/news/1041-allocation-of-estimated-payments-withholding#:~:text=Withhold...