Windows tight in corners

[Eric Muetterties]

When I push windows tight into exterior outside corners they connect and leave a set if lines as though they are connected with each other even though I have the casing set for "O".

Is there a way to stop this?

I am tired of editing the elevations to strip out these extra lines. It is quite common here to have aluminum windows with no trim in stucco and have them tight in the corner with a 4 x 4 in the corner.

Thanks in advance,
Eric Muetterties