The adult looks a bit like a Lanard Horse Play Prance N' Paw Stallion, but I can't find any info to suggest it came in black like this or with a foal.
Perhaps it's even a knockoff of a Lanard? I have plenty of knockoff Lanard pony toys, it's funny that there are fakies of fakies. I have a couple moulded Lanard horses too, with only neck articulation (no leg), and they have the Lanard company marking on their belly I think. In fact, I think one of mine is a Lanard Triple Crown Beauties Kiss 'n Nuzzle Mare, which is in a different pose than these, but I haven't got it on hand to check.
Do these have any markings on bellies or legs at all?