Get him to ask and if nothing changes then go no contact, it'll save you a lot of hassle further down the line.
MIL greatly favours SILs children over mine and DHs even though they are all the same ages and genders (two 4yo boys, two 2yo girls). She has her other GCs for sleepovers, takes them on outings, they have piles of toys at her house, she buys them clothes and bakes with them and all sorts. DD and DS got a half hour visit once every few weeks - we live closer to her than SIL to boot, all within walking distance but MIL has to pass our house to get to SILs. When DD was small she was in hospital, MIL didn't even phone to see how she was never mind visit. For DS 2nd birthday he got absolutely nothing from her, not even a card, because she'd been "too busy" to get him anything. Ditto his second Christmas, she asked if she could post his Christmas gift to him because she was too busy doing Christmas things with her other grandson. DH told her not to bother.
She cancelled plans, most notably the weekend before DS 4th birthday when her DP was "too ill" and apparently spent the day at the walk-in centre - except that was bullshit and she was actually at a Chinese restaurant with SIL and the other GCs. I could list and list the ways she played favourites but the final straw came on DDs birthday. For his birthday DS (age 4) got £5 in a card that her DP delivered the minutes after bedtime, when I asked where MIL was "she's at home with The Kids". Two weeks later DD (age 2) had her birthday. MIL rocked up to my door with balloons, cards and a Vtech tablet for DD. That was it. I told her (with backing from DH) that I already know she plays favourites with her grandchildren but she will not play favourites with my children and that I could not accept a reasonably expensive gift for DD when all DS got was five £1 coins. She took a massive strop, played the victim, cried, said she treats all of the children exactly the same, called me evil and spiteful, etc.
Not once did I say "you cannot see the children" but she hasn't spoken to us since and has told people that its because we've banned her from seeing them. We haven't and a few months ago she tried going via FIL to see them. DH told FIL to tell her that if she wants contact she needs to speak to us, their parents, and left the ball in her court.
Needless to say, she hasn't bothered. So now she is banned from seeing them as DH and I have decide that if she does try to contact us we won't be returning the attempts and if she does come to the door she will find it closed in her face. It's too late, she's had chance after chance and has blown them all. Lately she's started driving to our estate with her DP and parking on the corner at school home time as I'm coming past with the DCs which is both creepy and annoying. They drive off as soon as we've passed by. And I'm due a baby next week so no doubt she'll try contact us then.
Cutting her out is one of the best things we have done to protect our children from her manipulative behaviour and favouritism, DH has emotional issues going back to his childhood (she favoured his sisters over him) and we don't want that for our children.
No contact is a big step and be prepared for pressure from other members of the family (step-FIL thinks we should forgive and forget "because she's family) but if she's bringing you misery and her relationship with your DD is of no value then do it, you'll be happier. The label of family doesn't give people the right to treat you like you're second best.