Bruce Wayne had honestly not been intending to have any more children. Honestly, he hadn't even been intending to adopt anymore. Of course, like Tim and Barbara there were always kids that weren't technically 'his' but made it on the Christmas card. When he went out on patrol with you, his current partner (for the sheer fact you figured out his identity), he had not wanted to find a baby. He hadn't been thinking about it. Honestly.
But when you dropped into the alleyway, so damp and cold, and pushed aside a blanket to reveal a wriggling little baby, he lost all sense of responsibility and decided that this, this baby, was not going to be left.
The rest of his kids had given him similar looks to Alfred. But they'd all cooed over the little girl who was now bundled into the new blanket and clothes Bruce had bought her. It was decided he and you would go to the authorities the following day.