For the future - cases 1 & 2 you should be able to solve / merge together by disabling some or all autoClear options on the second render callee (if you render second call with effect composer, you should disable clearing on RenderPass instead.) But, in this case, it probably won’t solve your actual issue.
As for how to actually solve the issue - maybe this would help 
(if you don’t want postprocessing outlines) ?