If they are carrying heavy loads this will impact the amount of fuel that they can carry.
When operating within the US a routine transport job may be used as a training opportunity.
The C-17 flight of three aircraft when joining up with the tanker effectively become one entity and declare that they accept responsibility for safe separation.
In doing so all the aircraft in the formation except for the leader turn off their ADSB.
The C-17s are tactical airlifters that need to practice formation group refuelling procedures regularly to maintain competence.
The receiving aircraft have to fly accurately in a box just a few yards wide in close proximity to the tanker.
In my eyes this looks quite routine.