So far, all the information I am finding is that I can travel to a country with bilateral agreement and stay for 90 days but I should do it at the end of my trip. Here is my circumstance:
I wish to travel 60 days in a Schengen country (Spain), then spend 60 days in a bilateral Schengen agreement country (Poland). Then, I wish to return to Spain for the remaining 30 days I did not use in the beginning, and fly back to the USA from there.
If I produce receipts that I was in the bilateral agreement country for 60 days, will Spain let me back in?
Another way of asking this is do the 60 days in Poland count against my total of 90 days I'm allowed in Spain?