Thank you, @ArtleyWilkins

Conversations definitely are a great idea!

I spoke with our daughter recently to ask if they told other family members and whether it would be okay if I told their aunts and uncles about getting married. They sounded uncomfortable and pointed out that my sister and her husband are very religious and might not approve. Then I wondered if their partner would lose her disability benefits as a result of the combined incomes. That brought up the idea that they might not get married officially; rather they might have some symbolic ceremony.

So I'm getting more involved with both of them, but my wife is still out of it.