First of all dealing with new grandparents is such a hard one. I had so many issues with MIL once my first was born and still have the odd issue. I think what happens is that we have it in our head how we want things to be and they have their grandparent fantasies in their head. Of course reality is often very different. It can be so overwhelming I think for both parties, but I think especially the mum dealing with being a mum for the first time.

I think they are overstepping their boundaries, they should always ask rather than assume with anything to do with your family, not just your DS. I think it is really your DH's place to say something, but if he is not willing to do so then you might. May something like "Look we are very private people and whilst we understand your excitement at becoming grandparents, we are finding it a bit overwhelming. Would you mind asking first before organising something etc and please respect us when we say no" Now it would be good to "offer" them something to make them feel special, like help organise a birthday party, or can they come and hold him whilst you get something frivolous done around the house. I got my MIL on side by getting her to knit a heap clothes for the girls, it helped keep her occupied and I like knitted jumpers. So win win!

Initially MIL was overly involved, she had come over to help after DD1 was born. I had an emergency c-section and was having feeding troubles. I found her so overwhelming, she just hovered the whole time. In the end it took me yelling and swearing at her. DH was just useless and I still have not forgiven him for that time. We managed to work things out, nothing was fully discussed, but we just took baby steps. She still interferes and many times I still want to throttle her, but she does love the girls. I am so glad that she does live in another state, even though sometimes for the girls I so wish she was here. As the kids get older it is so much easier to let grandparents have a greater involvement.