Make a profile, where I can swap out my cabs? 4x12 and 1x12... Is that a merged or direct?

Do you mean a profile that you use with real

cabs or do you want the cabs digital too?

In that case why not make 3 different profiles? They could be three studio profiles, one with each different speaker. That should technically be the same as when you turn your head into a direct profile and then profile the cabs (a process for which you need to attach the amp head anyways).

Sorry, I might not quite understand your question.

From manual 7.5 page 300. Direct Profile - only the head gets profiled. You still have to have a cab hooked up or the head will blow.

Merging requires 2 separate profiles - a) direct, and b) studio (head and cab with the cab mic'd).

In order to achieve what you are suggesting you would really need 3 Direct Profiles and 3 studio profiles and then make merged profiles from each pair. This is due to the fact that each cabinet will have different impedance curves which will affect how the amp itself responds. However, in reality any difference is likely to be minimal so you would probably get away with one direct profile and 3 studio profiles and merge each Studio version with the same Direct profile.

This would give you the true separation between amp and cabinet and the ability to then use these 3 cabinet presets with any future direct profiles you make. When combining you 3 cabinets with other direct profiles there is no need to merge again (that is not what merging is designed for). Simply load the direct profile and the desired cabinet preset and store the rig.