ModularFuelTanks, InterstellarFuelSwitch, and ConfigurableContainers do not play nicely with B9PartSwitch, so the autopassthrough configs are disabled when those are installed. It would be nice to address this. Possible solutions:

• Provide structural copies of the parts that have FreeIva support. This has the downside of cluttering the parts bin, and if these parts are only conditionally available then it could cause problems for people if they removed the fuelswitch mod and the parts disappear. So perhaps this could be an optional patch.
• Provide an optional passthrough-for-all patch that enables FreeIVA traversal without affecting mass or resources.

See also #183, #188