Hi Vanessa,
the only objects that are shared between sharing contract and linked provider contracts are counters - in a sense that linked contracts can access the counters of the sharing contract.
It's not possible to share (=jointly use) a service defined in a sharing contract from other contracts...
With the newly introduced features of allowances, sharing contracts can also be used to define allowance buckets that can be accessed from linked contracts. But business-wise this is similar to the shared counters.
Best regards
Stefan