TBH, OP they might choose not to come to the funeral, particularly if they're a distance away.
My husband and his ex separated (and then divorced) after his ex took up with someone else. Their children were adults and had left the family home.
The ex kept the family home, so when the kids returned for visits they stayed with the ex and her partner[s]. (The first boyfriend died.)
Before anyone asks, yes - they could have stayed with us. However, when we organised this, they didn't show: "Mum thought we were staying with her and we couldn't hurt her feelings."
They did visit while they were staying with their mother, but when DH was ill he had one half hour visit from one of them one of the times he was in hospital, though they did attend the 70th birthday party we organised for him.
My husband told me that he didn't think the kids would come to his funeral. I reassured him that they would come. My husband was right. (To be fair, it was during lockdown, but at least one of them could have attended.)
It's my experience that if people don't make the effort while someone is alive, they certainly won't make the effort when they die.