Hmm,
it's true that there was an awful lot of 'enhancement' going on in the 80s as far as live performances are concerned. I think it all started with a revelation in 'Sounds' in the early 80s that the Michael Schenker Group had a hidden guitar player at one point.
I was lucky enough to have had free reign to wander around wherever I wanted at that Hammersmith show and saw the soundcheck as well as the gig. Lanny Cordola was certainly playing everything as far as I could see.
Can't comment on Gregg's contribution to the records. It was seemingly his band (Gene Simmons' name!), so he could do as he liked. But, let's face it, how are we to really know whether any of our favourite musicians actually play on everything? You just have to look at Kiss as an example and Frehley and Criss' contributions.
With regards Angel, Mickey Jones was reported not to have played a note on 'On Earth..' I recall reading an interview with Eddie Kramer where it was alleged that Punky Meadows played bass.