From my perspective:
1.You need check if this staff got insurance paid in another company first.
2.If this staff got no insurance paid by other company or approval of retirement.then it`s not part time from legal perspective.
3.You will have big riskes when this staff got accident.
4.According to current HR policy here.Even you sign a part time contract.Labor court will not support you 100%.
5.I will recommend you that you need pay accidend insurance for this staff as your risk control.At least it will cover some cost of your loss.
Thanks.