We expanded the package feature and it's now possible to create what's called flexible packages. Here you can specify groups of similar resources, from which only one will be reserved when the package is reserved. The choice can be made automatically or manually, depending on your preference. This is very useful to make multi-dimensional reservations when the customer reserves e.g. a tennis court as well as one of the tennis coaches. See Q232
in the FAQ for different usage examples. The packages should now be used instead of resource dependencies for all new resources. Resource dependencies are still accessible but only for the resources which use them already.