In order for both Scotflight and SIM720 airports to work together you need to disable a few files, just rename the file extension to .OFF i.e. AF2_EGPO.BGL.OFF
Stornoway
Files are located in Scotland_Main/Scenery folder
000_EGPOStornowayFSX.BGL
CVX_StornowayHarbour.BGL
EGPOStornowayFSX_OB0.BGL
EGPOStornowayFSX_OB1.BGL
EGPOStornowayFSX_OB1X.BGL
EGPOStornowayFSX_OBX.BGL
EGPOStornowayFSX_TEXP.BGL
EGPOFuel.BGL
EGPOFuel2004.BGL
AF2_EGPO.BGL
Oban
Files are located in Scotland_Main/Scenery folder
EGEO_Oban.BGL
EGEO_Oban_CVX.BGL
Oban_NorthConnel_OBX.BGL
ObanAirport_fences.BGL
Files are located in ScotflightLibraries/Scenery folder
Oban_VehiclesObj.BGL
ObanAirport_Obj.BGL