It says in SA YD Siman 152 Sif 1 that it's ossur to go to a wedding (seudah) that a gentile is making for his son. The Shach and Taz both discuss over there if for reasons of "aiveh" if one is allowed to go (meaning that the gentile would get upset with you if you didn't come.) The Shach has a tzrich iyun in this. The Taz however is seemingly more machmir.

While it seems from Shulchan Aruch that it would be a problem to go to the seudah (assuming as well it's in a hall and there is no other problem of entering a church, etc.) Are there any heterim for this? Are there poskim that rely on the Shach in this matter? Would it help if along with having their own food would sit at a separate table?

(The person making the wedding let's say is a business partner or neighbor that one is friendly with.)

While I realize in a practical situation one should ask their Rabbi what to do, I'm asking here for sources on the issue and if there are any makilim in the poskim.