Moed Katan 8: No Mixing One Simcha with Another

3 mishnayot: Burial over Chol HaMoed, with a real difference of approach as to what it means to bury over the holiday. Also, digging a crypt or building a grave over Chol HaMoed in advance of a death is not allowed, but adjusting one that already has been prepared is acceptable. Plus, a laundry pond. Also, the issues pertaining to getting married over Chol HaMoed - a series of explanations why it's not allowed.