It has nothing to do with whether or not she is a "hong konger", and it has nothing to do with whether or not Mr Chan has divorced his ex.
I feel sorry to see what had happened to her, I agree to let her parents stay in HK during this difficult time as long as possible until she is physically and mentally recovered to look after herself, then she may be able to apply 居港權 for her parents later on for whatever reason... but at the time, if we are wishing her to have her parents here in Hong kong to support her, then extending their stay in HK can already do the job.