How do I approach this?

My in laws have been estranged for several years now. When our son was born we set some hard boundaries for them to swallow after my FIL was caught cheating, using meth and heavily drinking. We cut off contact when he began to get physically violent. Anyways my sons first Christmas my MIL showed up with no notice and then was angry that I didn’t wake our newborn baby to come see her. I was recovering from a horrendous labor, and subsequent csection on top of being a new mom and everything that comes with that. She wasn’t there to help, or anything like that and ended up storming out when I wouldn’t wake the baby. The Christmas after that she sent a box of presents over with my BIL. They sat in the garage for a few weeks before we donated most of them. And after that she stopped all together. My husband will randomly get a text from her - on holidays only. Happy Easter. Nothing else, no I love you, miss you or anything like that. Just a hit or miss message. The last time they spoke to each other she told my husband that she loved her other children more than him and that they were more important to her and that was just after she urged him to leave me. As if this was somehow my fault. I didn’t encourage him to cut contact, he made that decision on his own though had he not I would have definitely let him know where I stood. He knows now, but at the time he made it the choice was his own. We tried for awhile to keep a relationship with his mom, but she began to get angry and aggressive at every interaction. I know she was projecting her own misery onto us and our relationship which is happy and healthy. After she said those things to my husband he stopped trying, it wasn’t even so much that we cut her off, he just never reached out to her again and she didn’t even bother to try.

That was almost 4 years ago. Nothing has changed, boundaries haven’t been respected. Zero effort has been made on her part to mend things.

Well she just showed up with a huge box of presents for our kids calling herself Grandma and all sorts of BS. Our son is almost 5, she hasn’t seen him at all since his first birthday and she only saw him then because my sister in law made her come over and she’s never even met our daughter. I was so taken aback when I opened the door I didn’t even know what to do. She wanted hugs and loves from my kids which I told them they absolutely didn’t have to do. She’s not grandma. She’s never been a grandma to our kids. My best friends mom is more grandma than she will ever be and my own mom is an amazing grandma. just bringing presents doesn’t make her grandma but she seems to think that’s all it takes. Before my kids were young enough it didn’t matter, but now our son is just confused about who this cool lady is bringing him a bunch of presents and calling herself grandma.

We didn’t let her in and I took the box straight into the garage while we decide what to do. I would have left it sitting outside but I was just anxious to get her off our porch. I’m always civil, I don’t want my children to grow up being unkind, I just don’t know how to approach this subject with my kids. I thought I had a few more years, but now I’m terrified she will show up and try to use my kids as an “in”.

I used to worry they would try when my kids were teenagers to form a relationship with them, at least by then they could understand why we didn’t want them around, and my kids could make their own choices but this feels so much more underhanded.

I’m all for mending the relationship, but the relationship that’s broken is between them and my husband and I feel that before they have access to our children they need to fix that or at least make an attempt on their side.