Before getting into how to repair the siding problem, you should consider the entire context of the structural and enclosure system. Some frames are sip dependent for frame rigidity other frames can be fully braced and not wholly reliant on the diaphragm. So without solid osb on both sides a sip becomes very less meaningful as a structural element, so you will be left with the question, is the enclosure or the structure compromised? How many panels can be lost before the structure suffers? Ask the big questions before you decide what to do.

Rain screens, windows and flashing details are a bit of a devil to get right the first time, just try to get good advice on site and keep at it until the full line of questions are resolved into a reasonable solution before acting.