Sharing legal custody when you disagree about whether to immunize your children
One such approach could be to ascertain what research evidence is available to support each parent's beliefs and what decision-making process was followed. For example, having had a case of chicken pox as a child protects an adult against shingles, which can have lifelong and devastating consequences. Parents may have different reasons for believing different things and some are more "proven" than others, but there is research available on some issues.
It may be helpful to see published, scientifically valid references on the various issues and vaccines, and to compare them with current medical practice. What percentage of pediatricians, and/or scientific opinion, supports a particular point of view?