Is the maid considered a suckling mother to the child after she breastfeeds him without the mother's knowledge, and what is the most appropriate Sharia and legal action to take in this situation?

If the maid breastfed the child five times, she is his mother through suckling. The maid should be forgiven, not expelled, not sued, and the matter should not be publicized, as Allah Almighty says: ﴿So whoever pardons and makes reconciliation - his reward is due from Allah.﴾ However, precautions should be taken to prevent a future marital connection between your son and the offspring of this maid or whomever she breastfed.