I think it would be an asset if carts such as locomotives could pull resources from a cargo or chest cart, then a tank cart if that tank cart is attached to the chest or cargo cart.

This would especially be useful when using locomotives to create longer railway stretches without being able to supply water readily at such distances.

The biggest bottleneck to travel distance is water, fuel is very dense. If you want to extend range focus on tank carts.

Duplicate of #1372

While I get that is the current strategy to overcome this, the user should be able to automatically resupply via carts.

This isn't a duplicate of #1372 as it assumes that bug is fixed, but rather suggests the locomotive should be able to pull from two different carts at the same time.

Then it is a duplicate of #635

Not really.
#635 ended up with CovJ fixing the behavior mentioned so locomotives couldn't pull from multiple types of carts at once.

A single locomotive should be able to pull from tank and cargo carts attached to each other

Currently that behavior doesn't exist, and the behavior mentioned in #635 relies on the use of a oversight to work.

@Lilithvia That issue is not fixed. The behavior is not yet determined. As you requested, I will increase the priority of #635, but leave no more comment here. Go to #635 instead.

Will do