As you were told in a previous thread by scylla, they can't apply for any form of temporary residence unless they renounce their PR status.
They would need to qualify for work permits like every other person, with a job offer from an employer with a positive LMIA.
They could apply for regular TRVs or if you meet the income requirement, Supervisas. As visitors, they would not be able to work or be covered by healthcare.