When there is a child born out of wedlock and the mother marries and has a family. I know that you can seal the child to that couple using Step relationship to the husband.What if the child lives with his grandparents in the 1861 census age 2 and then was still there in 1871 age 12. Would you seal him to his grandparents with guardianship relationship?
I am just another 'lowly' User/Patron ...
[ And, I happen to be a Member o the Church ... ]
Just in passing ...
Short Answer: You can, if you consider such is needed.
Especially, if one of the Parents is not known or not recorded.
Better to be "Sealed", to one set of Grandparents, rather than NOT 'Sealed", at all,
Do not forget to pray about such, for the course you should take - follow the promptings of the Spirit.
The choice is yours.
Just in case ...
Here is a "Knowledge Article", in 'FamilySearch':
How do I seal a child to grandparents?
I know, that this may help/assist, somewhat.