My thoery is that after the election he is paying expenses from surplus campaign money. On the docs. I would expect any defense filing to be procedural and not have detail about proof that he is legitimate.
Only the big philly firm isn’t affiliated with the DNC or the Obama campaign like the other 2. And the philly firm wasn’t listed on opensecrets either, IIRC, but the other 2 were. e.g. The Sandler Reiff Young firm was charging ~$35-$45 thousand a month for months, but it doesn’t specify for what, exactly. Somebody knows, but not me.