Fourth cousin onced removed not in Family Group ?

Can someone clarify the definition of "up to fourth cousin" ? Shouldn't all "x removed" levels be included ? My fourth cousin added his 2 children, and one of them joined. The one who didn't join is included by default in my Family group, the one who joined is not included by default... is it a bug or a feature ?

Think of the fourth cousin boundary as 5 generations up and 5 generations down -- we can't include all fourth cousin n-times removed because there could be dozens of generations of those [the Family Group boundaries are there for both performance and some reasonable expectation of privacy]. So the cut-off is fourth cousin but not his or her children.

So for 3rd cousin all x-removed levels do included ? I think it should be stated more precisely, and I think they should be included also for 4th - it's not THAT big.

So 3rd cousin once removed (4 up, 5 down) is included, but not 3rd cousin twice removed (4 up, 6 down). Keep in mind that this range is also used for permissions on unclaimed / historical profiles, so including all descendants of any cousin could be tremendously large.