BoEF is the only source you'll find talking about that, really <.< >.>
Halflings are generally considered fairly 'stable' (they don't breed out of species easily) - it may be feasible with dwarves, but generally not elsewise, unless the other side of the equation is particularly fecund. ...which, it must be said, the orcish (including goblins) types are generally considered to be. So, you'd probably be flipping a coin.
Though in the realms, generally speaking, divine assistance to make couples that wouldn't normally produce anything actually do so, is not terribly unusual. Not common, but not unheard of either.
