Actually the above outline is incorrect. It should go:
As pointed out, Ollivander says the wand belonged to Bellatrix. Therefore the wand isn't hers, So it's Ron's. If we trace the path of the wand:
Bellatrix looked around, shocked; she turned her wand to face Ron instead. "Expelliarmus!" he roared, pointing Wormtail's wand at Bellatrix, and hers flew into the air and was caught by Harry,
So Ron is currently the master since he actually disarmed her. Harry did not.. Then
"“I said, drop them!” she screeched, pressing the blade into Hermione’s throat: Harry saw beads of blood appear there. “All right!” he shouted, and he dropped Bellatrix’s wand onto the floor at his feet. Ron did the same with Wormtail’s.
So Bellatrix tells them to drop their wands. I assume since they willingly dropped them this doesn't count as an official disarmament which explains why Ollivander later on said Wormtail's wand belongs to Ron since he won it (by actually forcefully taking it).
Anyway going on,
Draco hurried back to her with the wands.
So Draco just picked up the 2 wands: he didn't actually disarm anyone or overpower them. And Harry moments later wins Draco's wand:
Harry took the chance: He leapt over an armchair and wrested the three wands from Draco's grip
Wormtail's wand and Bellatrix's wand still belonged to Ron, Draco was just holding them. Therefore the only wand Harry won was Draco's.