SOPs and check lists can always evolve; the issue is when some sort of standard is discarded.
Who hasn't heard their FO bemoan that every captain likes things done differently? Whilst this fails to realise that every FO is different and needs to be managed in subtlety different ways, it does highlight that SOPs exist to allow a crew to operate cohesively with a fair expectation of what each other will do at a given point.
To the OP, insiduous changes should be guarded against and hence it may be worth advising your new colleagues that there input has merit but needs to be assessed and incorporated correctly.