Current sharing controller
The first strategy should be to not have to share current between two voltage sources.  There are some ways, but it's even better to avoid this in the first place.

Why do you think you need current sharing?  Do you need too much current for one supply?  Why not get a bigger supply?  If you're trying to use switcher chips and create your own supply around them, there should be ways to beef that up.  Perhaps you need a multi-phase switcher.  That's basically multiple switching power supplies with a common controller and evenly distributed phase relationship.

Step back and explain the problem you are trying to solve instead of asking about a single solution.