Personally, I'd be inclined to spread them out a little.
Especially if the parade is busy enough itself.
Without making it too much a "shopping trip" too, it gives you a second opportunity to do any bits and pieces around the 2 events, and not have too much stress of "we need to be X place by Y time" or DD whining about "when is Santa". (Not that either needs to happen, but you have less chance of it happening if things are more spread out).
It also makes the most of your and DD's energies.
My personal inclination would be that the weekend of the parade, go, enjoy the night out, do a few bits of shopping or whatever on the following day, and enjoy a nice lunch/hot chocolate and buns stop somewhere, and head home at a reasonable hour.
Then, whatever day you do the Santa event, go and do that, grab any other bits you wanted, another nice family meal together, and again head home at a reasonable hour. If timings suit, it might be nice to head home slightly after dark so DD can see the lights again, if everyone is still up for that (but I would have it planned but don't tell DD about the possibility in case anyone of the 3 of you has had enough and you need to leave earlier).
By being less pressured also, you have a chance for DD to look at things she might want to get for DGPs or if she wants to get a present for her new sibling.
And you might use the excuse of being in a toyshop for other things (new sibling, presents for other DCs in the wider family, a "giving tree" present or whatever, lots of toy shops also have new baby sections for equipment that might need to be bought even if only 1 extra bib/bottle for show!) to look at what she really loves on the 1st trip, and an opportunity is likely to then come up over the course of the rest of that and the other (or a separate one where DD is not with you) for 1 of the parents to slip back for the bestest thing ever, while the other minds and distracts DD (ooh, Daddy just had to go put some extra money in the car meter, or Mummy had to go and get a card for DNanna, or whatever).