i 'm not understanding your situation. you talk about a PONZI loss which you take a deduction of form 4684 and for which you probably should consult a pro. then you talk about IRC 163(j) which is a limitation on business interest without clarifying whether this is in relation to the PONZI scheme. Then there's the 199A issue. There would be no 199A loss if this is from a PONZI scheme.
We can't see the grantor trust letter and I don't understand everything that took place within the trust.
however, a grantor trust is a disregarded entity, so in short, the information would be entered as if there was no trust
for example, interest income would be entered for each payee on a form 1099-int
security sales would be entered through form 8949/schedule D
the PONZI scheme loss would be reported on form 4684 there are multiple options
