Can I make someone other than my children's father their guardian if something happens to me?

Question Details:

My kids dad and I have joint custody. Right now he sees the kids 2 to 4 days a month. He has no license, no "real job" (he works under the table) and not responsible over all. He doesn't support the kids financially now so how will that change? I want my parents or their godparents (my sister andbrother) to care for them as they are in there lives regularly. If I have a Will drawn up with 1 of my family members as the kids guardian will it stand? I would like it to be my family has them as I do now and the kids dad gets them still on his weekends or overnight as he gets them now. Important Notice