Ok I got object A and Object B. I use the attach function to make them one, single object. My problem is that I cannot target weld a vertex of the former object A with the former object B and vice versa. The vertex of the other object doesn't display as a valid vertex you can weld. I'm talking about "other object" although it's supposed be one object without any restrictions after attaching.
So how can I weld those goddamn vertices?