Remembering that the FamilySearch tree is a “one-world tree”, it wouldn’t be possible to record cousin autosomal relationships, as there would be too many for everyone. And most autosomal matches are living people anyway. But, the haplogroups for Y-DNA and MITOCHONDRIAL DNA should remain fixed for given individuals. In fact, knowing the haplogroup values for people is one way of disproving possible relationships. (It can’t prove them.)
To record a given haplogroup, create a “Custom Fact” under “Other Information” for your given ancestors. Custom Facts are viewable by all. For the Title, make it “DNA Values”, in the Description field put the actual haplogroup code, and in the “Reason This is Correct” field, put who the haplogroup belongs to with the testing company.
Similar to this:
I think it would be reasonable to record haplogroups for one’s direct paternal and maternal ancestors out to the point where a given autosomal match has shown the ancestor to be a MRCA (Most Recent Common Ancestor). Going beyond that ancestor is not verifiable without the given autosomal sourced trail.
The above comments are my personal opinions .