In essence the answer is quite simple. The CAA [SRG] would have to approve the radar vectoring procedures in conjunction with the RAF.
A letter of agreement between Inverness and Lossiemouth would then be entered into.
The other solution would be to place civil approach radar controllers at Lossie, with ADC only at INV.
All this comes under the heading of Politics.
On over 50% of days into INV , I make a visual approach anyway.