Final Schedule K-1 (1040) from trust. Line 11b has 3 supporting statements. One says "beneficiary's share of mortgage interest" (report on Sch A). Where on Sch A? Thx!

[jeff-lccredding-]

Do I add to my personal amount in Line 8a or add to Line 8b? If Line 8b, how do I identify this as from a 1098 in my mother's name with interest paid to the mortgage company?

[tagteam]

It appears to be in trust's name, not your mother's name. 

See https://www.irs.gov/instructions/i1040sca#en_US_2023_publink53061xd0e976

Most likely report it on Line 8b.