Celebrating a joyous occasion during the festival:
One is not to rejoice other joyous occasions during the festival days in order so the joy of the festival remains distinct.
Getting married: Remarrying divorcee: It is permitted for one to remarry one’s ex-wife on Chol Hamoed. [Some Poskim however rule that one may not hold a celebratory feast for such an occasion. Other Poskim however rule it is permitted. One may certainly be lenient to hold a feast on the next day. It is questionable whether one may re-perform a Kedushin ceremony during the Moed, if the original Kedushin was invalid. ]
May one celebrate a Bris Mila during Chol Hamoed? Yes.
May one celebrate a Pidyon Haben during Chol Hamoed? Yes.
May one celebrate a Bar Mitzvah during Chol Hamoed? Yes and so is the widespread custom.
May one get engaged during Chol Hamoed? Yes.
May one celebrate a Lechaim/Vort during Chol Hamoed? Yes
May one celebrate a Siyum Mesechta during Chol Hamoed? Yes.
May one celebrate a Chanukas Habayis during Chol Hamoed?
May one celebrate an Upsherenish during Chol Hamoed?
