Seeking PT Nanny/In-Home Childcare or Nanny/Babysitting Co-op

My husband and I are in need of a Part Time Childcare provider in the Grapevine Area. My husband has a full-time job that has alternating hours every two weeks (5a-2p/ 9-6a/ 2p-10p) and I am a freelancer who has contract work that most times requires out of state travel. We have a wonderful 12 month old, who typically can stay with either his paternal or maternal grandparents when necessary, but sometimes we are in need of someone who we can call upon to take care of our son when they can't. We are seeking someone who is flexible and affordable. Not sure if there is a babysitting or nanny co-op that would be willing to share their childcare provider with us when necessary. They can either come to our home or we can take him to your home.
Any suggestions for co-op services? Anyone interested in providing your service?