In a situation where one became an avel before Pesach, and shloshim ended during sefirah, would the avel be allowed to shave/get a haircut since he did not have an opportunity to do so before Pesach? Thank you.
If the aveilus is for a parent, the child has to wait about three months, or when people will rebuke him for not taking a haircut, even though shloshim has passed. However if the aveilus is not for a parent, then it is permitted to take a haircut during sefira.
Sharei Teshuva 493-7 in the name of Zera Emes, Chazon Ovadia Aveilus 2-pg. 294, Divrei Sofrim 390 ftn. 2, Hilchos Aveilus pg. 106.