Apologies in advance for the long post.
Myself & my partner are in a same sex relationship. Female. We have baby, both legally and equally their parent, I am biological parent. We are getting married later this year, wedding was booked pre-baby. It is a small wedding with 30 during the day and a further 50 at night.
My partner and her mum have a difficult relationship. It was good until her now husband came on the scene. Partner and stepdad don't see eye to eye AT ALL, both fiery characters, he has never agreed with her sexuality, generally made her teenage years very difficult. The arguments resulted in her having to stay with her grandparents permanently. She has 2 (adult) sisters who love the stepdad very much and call him "dad". She has always felt like an outsider from this perspective, not fitting the conventional family mould, they have a family group chat without her in it, etc. Regularly meet up and don't invite her.
Her relationship with her mum has improved somewhat in recent years. Can go weeks without seeing each other but do text several times a week. Mum has admitted to her that she sees it wasn't "all her" back then and the stepdad was at fault too. Partner felt v much like mum chose stepdad over her at a time when she really needed her mum.
Her mum told her previously that if she had a child with a woman, she wouldn't view them as her grandchild. Since denies saying that.
When we booked our wedding, we extended an invite to both mum & stepdad. Mainly as it'll be the first time her mum sees her biological dad in 20+ years since their divorce and we thought she'd welcome the support. Her mum quickly told us that the stepdad won't be attending as he doesn't agree with same sex marriage.
Since the baby was born, her mum has referred to herself as grandma and buys him gifts, etc. First baby in the family. She also makes a point of saying that stepdad has picked some of the gifts and looks forward to teaching him sports etc. when he's older. She doesn't visit often, they live 50 minutes away. She is always welcome to but doesn't drive (stepdad does). Stepdad has met baby once, when we took baby to their house. They regularly visit partner's sister who lives further away than we do.
Partner queried this with her mum, saying that it doesn't make sense that he has such strong views towards same sex marriage but apparently not babies conceived in the context of a same sex relationship. We feel like they are mutually exclusive. Her mum said it's just the marriage part he doesn't agree with. Asked if it was a knee-jerk reaction saying he wouldn't come to the wedding and was then told he would come after all. She also said - quote - "he would never say anything to the baby, just like with drug users children it's not their fault how they were brought into the world". I can't see how you can compare a much loved, much wanted baby to an accidental conception by a drug user.
She signed off the Christmas card to baby from grandma and granddad.
She has made irritating comments almost every time we see her. On one occasion when she came to our house she said "what's the baby even got to do with partner" due to baby having the same surname as me, partner will be taking my surname when we marry hence the reason behind this. Baby has partner's surname as middle name. Her mum doesn't have this surname either since she re-married to stepdad many years ago.
She regularly makes comments about how she never gets to see the baby and it's so unfair. As I said, she is welcome any time but always expects us to drive to see her, even just after the baby was born. Baby is a matter of months old currently. On my partner's few days off it's difficult to find a time to go to see her - the stepdad has a hobby which she accompanies him to, even though there is no requirement for her to do so. This takes up several days in the week. She regularly makes comments about how I always take baby to see my mum and we always keep my mum informed and not her. My partner tries her best to update her as quickly as possible but works 40+ hours a week (shifts) and frequently sends pictures, etc. I am very close with my mum, as is my partner. Partner feels she needs to make a conscious effort to keep her mum in the loop so she doesn't kick off.
Her mum and stepdad went to partner's sister's house recently to help build a fence, took several days to complete. Her mum took no part in the fence building but just accompanied the stepdad. She could have easily got him to drop her off at our house en route to spend the day with baby but didn't suggest doing so.
After discussing with friends, we felt it wasn't appropriate for stepdad to be at the wedding, given his views and given she doesn't get along with him. She tried to sensitively tell her mum this by saying that the guest list numbers are tight, we have ran over and when we drafted the list he had said he wasn't coming. Her mum kicked off royally, saying we will need to cut other people off the list to allow him to come. My partner said "why would we allow him to come over people we actually see regularly" and her mum then started going on about how she never sees us, how she never gets to see the baby, how we always go to see my mum, etc etc etc. She said when we do go and see her we always cancel on her but wasn't able to name a time this has ever happened. I think she's referring to occasions where we've had a loose time to visit and the baby has been sleeping, she's then said "just leave it then". She then said "when you say a time, 12 becomes 1, etc". We have a young baby who feeds on demand, we're obviously going to make sure they are happy and fed before we set off for 50 minutes in the car and It makes absolutely no difference to her what time we go at. She has 3 kids of her own and should know better about how hard it is to get out the house sometimes. This particular argument resulted in her mum crying, saying she'll make it "easy" for us and won't come to the wedding, then left.
Partner text her mum soon after saying she was sorry that she was crying and her mum apologised for taking everything personally. She text again a few days later saying she will pay for stepdad to come. It doesn't come down to money ultimately although this is the way my partner presented it to her to try to spare her feelings.
My partner feels like she should explain to her mum that she just isn't comfortable with the stepdad coming due to his views and she'd tried to spare her feelings but is worried about her mum falling out with her and ceasing contact as their relationship is better now than it was for many years.
We also don't particularly want baby around the stepdad given his views towards us but feel that our feelings aren't taken into consideration in this and we're being made to feel unreasonable - like he has a divine right to see the baby. He's not a toy, we want to raise our child to be strong and proud to have two mums and not feel like he is disadvantaged. Everyone else in our family and friends are very supportive and our baby is extremely loved.
Again, apologies for the long read. Thoughts and suggestions on how to navigate this would be welcome please.