According to Mormon Church, can "co-parents-in-law" marry?

Question

Same question as here but for Mormons/LDS. I don't see how a married couple's becoming step-siblings is any different from step-siblings' become a married couple. It's just a matter of which comes 1st.

Suppose Alice and Bob are widows (or single adoptive parents or unmarried biological parents or whatever) and their respective children are Charlie and Dalia. Suppose all 4 are not married (or were never married or whatever, depends if widow or not) and none of them have ever divorced or annulled.

If Alice and Bob marry, then (I think...) Charlie and Dalia cannot marry. But if Charlie and Dalia marry, then can Alice and Bob marry afterwards?

Edit for Mormon case specifically:

I'm curious about the Mormon case given how they're so into family particularly family trees and stuff. I'd like to see for example how step-sibling marriage messes up their family tree records.

Answer 1

TL;DR: The status of the children has no bearing on whether two people can marry, as far as I can tell (except if local laws would ban that marriage)

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I checked the general handbook, and as far as I can tell, these are the guidelines that apply:

• civil laws apply to civil marriages (obviously)
• no same-sex marriages
• no plural marriages

For sealings (which can be seen as a religious marriage, but isn't quite that), since a couple has to be married in order to be sealed, the same restrictions apply, in addition to all conditions required to be able to enter the temple, none of which apply here. The status of the children appears nowhere.

When two parents are sealed and then have children, those are automatically part of that covenant and receive the associated blessings. When a couple gets sealed that already has children, those children can be sealed to their now wedded parents to be a part of that eternal family. The only restriction for adult children is that they too need to be endowed (so have made temple covenants of their own). I don't see anything related to the children's wedding status.

The church does condemn incest, and the now-step-siblings would be included in that, but I have strong doubts this situation as described would by reasonable local leaders be seen as such. Again, local laws apply.

Since a comment asked whether this situation messes up family tree records: Only if you maintain them wrong. The records need to able to record any messy situations, including plural marriages, unknown fathers, adoptions, and so on. FamilySearch, which is used a lot by members to do their family history and is the source of information for the proxy temple ordinances, can easily record multiple parent pairs, for example. We perform our proxy ordinances (sealings are most relevant here) for all these pairs, and let God sort out our mistakes in the afterlife.

For example, in life a woman is to be sealed to only one husband, but in proxy ordinances we would seal her to all her husbands and let God and the dead decide and fix what is right.