Actually:
1. Patent agents are not allowed to practice part-time at present.
2. According to the Measures for the Administration of Patent Agency, if a law firm applies for patent agency business, there should be more than three full-time lawyers who have obtained the qualification of patent agent to practice in the law firm.
In other words, at least three people in the law firm are qualified as lawyers and patent agents at the same time. Only the patent agent qualification is not enough.