The obvious answer (which you have probably though of) is to charge the owners for damage done top common property by their tenants. This is above and beyond repairs and maintenance and is covered in the Act.
The other option might (and I stress might) be to pass a by-law that every owner has to pay a tenant registration fee for every change of tenancy, regardless of how often this occurs.
I'm not sure of the legality of this but if it applies to all owners and is passed by 75 percent at a general meeting, it could even things out neatly. You could justify it by security requirements and administration charges and again, I think it's a requirement under the act that every change of tenancy has to be notified to the OC.
This is what Section 119 says:
119 Notice to be given to owners corporation of leases or subleases
(1) If a lot is leased, the lessor must give notice of the lease, in accordance with this section, to the owners corporation within 14 days after the commencement of the lease.
Maximum penalty: 5 penalty units.
(2) If a lot is subleased, the sublessor must give notice of the sublease, in accordance with this section, to the owners corporation within 14 days after the commencement of the sublease.
Maximum penalty: 5 penalty units.
(3) If a lease or sublease of a lot is assigned, the assignor must give notice of the assignment, in accordance with this section, to the owners corporation within 14 days after the execution of the assignment.
Maximum penalty: 5 penalty units.
(4) The notice must specify:
(a) the name of the lessee, sublessee or assignee, and
(b) the date of commencement or assignment of the lease or sublease, as the case requires, and
(c) the name of any agent acting for the owner in respect of the lease or sublease.
It obviously doesn't cover your question but it may be the key to an answer in a roundabout way. Anyone else with any practical suggestions?