Thanks rkenia852, I did get a reply from IMMD.. posting it here so that others can refer to it as well.
" In general, if a person ceased the employment with the company, he/she should leave HK as soon as possible as his/her condition had changed. If he/she has to settle his/her personal affairs or for any personal reason he/she cannot depart right away, he/she may stay until the last day of the visa validity subject to the condition that he/she shall not take up any other employment, whether paid or unpaid, without approval of or unless further approved by the Director of Immigration. On the other hand, non-permanent residents such as those on "student', "employment", "training" of the Hong Kong Special Administrative Region, irrespective of their nationality and type of travel document held, do not require a re-entry visa to enter Hong Kong provided that they return within their valid limit of stay and that the circumstances upon which they have acquired their residential status remain unchanged.
In other words, you and your dependants may stay and travel in & out of Hong Kong within your current limit of stay granted if there is no restrictions or conditions stated on visa labels. Dependants may work or study during their existing limit of stay in Hong Kong. If visa label shows that there is no specific condition of stay but only the limit of stay (till xx-xx-xxxx), and there is no endorsement with a condition of stay that "Employment is not permitted", the holder of the dependant visa label is lawfully employable during the permitted limit of stay."