If follicular ruptures on 26th and the intercourse was donr on 25th, 27th and30th. So possibility of being pregnant is on which date.

Same donor, right? As always, a woman has to separate different men be at least 2 weeks, to avoid questions about paternity. The 30th is perhaps too far away, but these days are too close to call, and it doesn't matter anyway because any predicted calendar date is just an estimate. For example, if one predicted the 27th as when egg met sperm, it could still could have happened on the 26th or 28th.