My husband and I have very different needs when it comes to our mattresses.  The solution for us was to go with a split king, so we could each choose a mattress that would work for us.  With my very bad back, I also decided to get an adjustable bed for myself and we splurged on one for the DH as well.  We have some issues negotiating the divide between the different mattresses when we cuddle, but the only real problem we have is that the beds split apart.  Our bedroom does not have carpeting so there is nothing to stop the beds from drifting a bit to begin with.  Since the beds are separately adjustable, I don't think we can use a bridge and I can't see a place to jury-rig some sort of connection between the adjustable frame bases.  We have been using plastic cable ties around the legs to hold them together, but eventually they loosen up enough to slide down and slip over the small lip at the bottom of the leg and above the wheel.  The beds can then fly apart at very unfortunate times!  Has anyone else had to deal with this problem?  What have you found that works?

The solution are castor cups.  You can definitely find them on line and maybe at a Lowe's or Home Depot.  You will need to install them underneath each castor on both adjustable bases.  Also the store that you purchased your mattresses and adjustable bases from should have access to them.  They probably should have suggested them in the first place.  The cups will also help protect your hardwood floors and reduce the noise that any massage/vibration feature will produce.