I have 2 Male Flemish giants. One of them is about a year and a half, the other is about 6 months old. Both are neutered. I've been going about the bonding process for a couple of weeks with no luck. There isn't any progress at all. Thumper (the older of the 2) is free roaming through the house. Ubu (the younger) is still in a cage but comes out several times a day. Both are litter trained but Ubu likes to mark his place everytime I try to bond them. Thumper doesn't do this. Is there a way to help this process??? I've been told to place them in a stressful situation together, such as a car ride. Will this help??? I really want them to get along so they can both be free roaming about the house.