Not sure how familiar you are with the objects involved, or their properties, but this does sound relatively easy to do. There are two main categories of constraints in sketches (geometric & dimensional). Within each category there is a 'base type' (GeometricConstraint & DimensionConstraint), and more specific types, for different purposes, that are 'derived from' that base type, but have more specific properties than the base type. Anyways, the main property you would need to be working with is: DimensionConstraint.Driven. It is a Read/Write property with a Boolean type value. Also, each DimensionConstraint has a Parameter associated with it, which can be obtained with the DimensionConstraint.Parameter property. This is ReadOnly, which just means you can not set a different Parameter object as its value, but it does not mean you can not change the value of the Parameter object itself. You will notice that when you change the value of the Driven property, that changes the Parameter associated with it between a regular ModelParameter and a ReferenceParameter in the Parameters dialog. You can use this Parameter object to identify which constraint you are dealing with, as long as you know the names of those Parameters, or have renamed them.
With that in mind, you could have one or more Boolean type UserParameters specifically designated to controlling pairs of these (one that is Driven, and another that is Driving). That Boolean UserParameter could be put into an iLogic Form as a checkbox control. Then, if using an internal iLogic rule, including that blue, unquoted boolean parameters name in it, that would cause that rule to run whenever the value of that parameter changes. Within that rule, could be some code that toggles which of those two DimensionConstraints is Driving or Driven. Not exactly a 'direct' connection, but possible to automate with iLogic this way.
Just some food for thought that may help you during your development.
Wesley Crihfield

(Not an Autodesk Employee)