@Zoobaloo
I would only invite your DD.
There's no way I would allow my DM to be put in such an uncomfortable position, having to share one of the most important life events with the OW.
Awful situation for both you and DM to be put in by your DD.
Not only have the pair of them ruined your DM's marriage, caused her untold pain (I imagine) the new wife is nasty to and calls your DM names, no way would she be invited.
My DM would come first, she'd be my priority.
I can't actually imagine how awful it would be for your DM, would the OW turn up dressed to kill? (to try to outshine your DM)
Would she be loud and proud, make her presence known?
Expect to sit at the "Top" table (she'll definitely expect to sit next to your DD)
Photos, I assume they'll expect to be in all the family group photos (slap in the face to your DM)
There's no way I'd subject my DM to that, it would be so upsetting and humiliating. I can almost feel the knot of anxiety that your DM must have in the pit of her stomach at thought of sharing your special day with these people.
The whole issue seems to be about what your DD and the OW wants, you dont want her there and neither does your DM.
A difficult situation for you and upsetting if you want DD to attend but theres no way would I invite the OW, invite DD then let him choose to come alone or not attend, be prepared for him not to come.
If the OW had anything about her she'd be saying "I won't come because it will be very awkward for everyone"
What an awful position to be put in by your own DF, I really feel for you and your DM ❤️