Trust withheld taxes... how can that get reported on a K-1?

My mother passed in 2023 and in 2024 her Trust, with EIN, received 1099s, one of which had tax withholding.   I want to help my dad issue a K-1 to himself (sole beneficiary and trustee) so he can report the income on his 1040-SR.  He tells me he is responsible for the tax not the trust.  K-1s do not have a spot for tax withholdings.  Am I stuck needing to file a 1041 and pay the tax due at the Trust level?  I doubt enough was withheld.   I'm confused and we should probably use a tax expert.  I'm a CPA so my dad thinks I know tax!  Thanks in advance for any help!