Putting a mask on top of another mask? (Premiere Pro)

So I'm doing some green screen work (which I admittedly did not do very well when shooting) and I need to do some masking around and inside a pair of glasses. I masked around the glasses but now when i try to mask the inside lens of the glasses it will not work, inverted or not...I figured this could be because it is "Mask 2" in the layer and needs to be on top of mask 1, however I cannot simply drag the second mask on top of the first in effects controls. I've also tried duplicating the layer, putting it on top, deleting the first mask and then creating the second one, this did not work either. The included pictures show the first mask around the outside and the second mask "trying" to mask away green screen errors in the lens.

Side Note: I have multiple green screen clips I need to combine to create one video.

Am I just making a fundamental mistake with the masking? And are there better ways of going about this? Thank you!