I agree on the attachment detachment.. my question was on similar lines to how CENTCOM operates. If as you say a squadron of tanks from Multan was sent to FATA.. does the responsibility of logistics and supply for it end up on the Multan Corps or will the unit that requested the support be tasked with it.
It depends upon the status of command, in simple words, the level of attachment. For example, being "under command for move only" would mean that the unit can be moved by the commander to which is it is attached, but may not have guaranteed fire support available to him. Logistics of the 'supporting unit' in this case would be the 'supported commander's' baby. Let's say a unit was 'In Support' for Phase - 2 only', so this would mean that the supported commander cannot order the unit to move, so logistics might remain with the parent formation.
In simpler terms, status of command related to two things, 'movement' of a unit or the 'fire support' of that unit. Then there is another thing known as 'command or control'. Command relates to movement, control means control of fire support. If command and control of a unit is centralized, it would mean that when ever the supported unit commander asks for fire or movement of the supporting unit, it will be done after the actual commander of the supporting unit approves it. This would then have different connotations for logistics. Normally, command is left centralized, and control is decentralized i.e an infantry CO cannot move artillery guns but can get fire from them without involving the artillery CO.
Armour component is usually given under command. Artillery is seldom made under command, it normally is in 'direct' / 'in' support or 'reinforcing' role - all having different connotations as regrades to movement, logistics, provision of guaranteed fire support etc. Air support or aviation support is routed in another way = Combat aviation have its own status of command whereas Cargo aviation its own. The Engineers units can be made under command, LAT/HAT also. Air Defence have their own status of command for various types of situation. For a typical defenceive operation it would mean something else, while if it is attached during offensive, it would be different, Even within the offensive, if it is an Assault Against Water Obstacle or FIBUA or an Advance and Encounter Battle, all would have different connotations.
So in short, i cant just tell you if a unit of armour operating in FATA from Multan would be provided with logistic support by whom. It also depends of the location of the unit. e.g. Logistic installations can be static or mobile, be in the Area of Operation (AOO) already or be stationed there permanently or might have been moved from the rear after there was a stretch. So, it varies.
The thing to remember is that all of this is very clear, as proper orders, to include Operation Orders (OO), Administrative Orders or Instructions (we have a different way of handling 'orders' and 'instructions') are issued well before an operation has to commence which spells out the status to command to the very last phase. If you have seen an OO, you might find that it gives details for all the phases like till phase 7 which has to commence after 10 days!