Hi there, just wanted to reply as I am in a similar-ish situation. I married a widower; the kids were 10 and 13 when we met.
In my case the kids' maternal grandparents were already deceased. But my DH's father and stepmum actually were the ones who had trouble accepting my presence. My FIL's wife had been close to First Wife, and was clearly of (and outright stated) the view that DH should not have remarried at all. It affected the relationship between my DD and her grandparents badly...they didn't really acknowledge her for a long time, and didn't include her when they sent gifts/cards for the other kids. Eventually my DH confronted his father about it, and to his credit, FIL apologized and made more of an effort with both me and our DD. (Sadly, FIL has since passed away - but I am so glad it ws sorted out a bit before he died.)
Not exactly the same, I know, but I do empathize with your feelings about being judged/not matching up. There are a number of First Wife's friends who are still in DH's life, either because they are his friends too or because they want a relationship with the kids, and while some have been more welcoming than others, there are always complicated feelings that can pop up, and I do always feel a bit more 'on my toes' around those people than I'd like...feeling that they are judging how I act around the kids, or how clean the house is, or my clothes, or whatever! It is not entirely rational, but then, I know if I were in their shoes, I probably would be keenly aware of the absence of my friend and also maybe watching to see if her kids were happy...It is tough.
As for what your child calls them - I don't see why it has to be the same as the half-siblings, and in fact that might be more confusing for your own child. My DSCs don't call my parents 'granny' or 'grandad', they just use their first names. My DH has two stepmums, so the kids all have two step-grandmothers. The DSCs call them by their first names too. My DD calls my parents 'Grandma' and 'Granddad', calls one step-granny 'Nana First-name', and the other just by her first name (that's the one who we are less close to).
You haven't mentioned if there are other grandparents, but keep in mind that they might have feelings about 'sharing' the title as well.
Could you have a quiet word with the GPs and say you know how hard this must be for them and you will never try to replace the children's mum or their daughter but you do love them all very much and hope to be a positive influence in their lives?
Aw you sound lovely. I expect the grandparents are lovely as well, just at the limit of what they can handle. I hope that makes sense. I have a severely autistic son and in the early years I found it very painful to be around children of his age, I didn't wish them ill, quite the opposite, it was just difficult as it was a stark reminder of what ds1 had lost. Now I don't feel that way (just a bit contemplative at times). I suspect it's the same for them but x10000000 in the pain stakes.
Why don't you (or dh) ask them. Say you'd like to have your child have them use a special name but realise it might be painful for them - and do they have anything in mind, or male some suggestions.
this is a bit different from the usual step situation but i would like some advice please
to avoid the dreaded dripfeed: dh was a widower when we met - and has two sons (now 12 and 14) who are still very close to their maternal grandparents. the grandparents are always nice to me - in a civil kind of way - but are obviously heartbroken that their only daughter died (cancer aged 36) and will never get over it. i'm not blaming them, but it means that however well we get on - and we generally do - it is a very painful thing for them to see me in what was their daughter's family (we moved house so i am not literally living in her home). they've never said as much, but i suspect they resent my dh 'moving on' when they obviously never can. (hope i don't sound horrible - just trying to explain without wittering on)
i get on v well with the boys - feel very lucky when i read these boards because i don't have the "you're not my mum" thing that often can happen
but the grandparents are tricky. i feel a bit judged - because i'm never going to match up to their daughter - and it's not like an exwife that you can slag off when she's not there - even to dh - do you know what i mean?
anyway, i am now pg with my first - and v happy and excited - and i want the maternal gps to feel involved but at the same time don't want to rub their noses in it or be made to feel like i shouldn't be as excited as i would under other circs
and another thing - what would they be called? i mean, my dss call them granny and grandad - would be odd for their half brother or sister to call them something else, but it won't be their grandchild?