I'm afraid I can't help - I haven't seen an ERP for ground handling operations. I would expect the detail to be very specific to the services provided and to the environment you operate in. In some respects I would even expect the ERP to be developed by the airport operator and the handling company's part to be detailed there.
FWIW, I would expect the structure to contain
- a clear scope for the plan,
- the triggers/initiators to put the plan in action,
- clear decision-making responsibilities and authority, and
- detailed procedures for the events covered - including checklists and notification etc.
It's not really going to follow the structure of a SMM but is going to form part of an effective SMS. The SMM should explain how the ERP is developed and maintained - who is responsible, who must be involved and so on, and how often (or when) it is reviewed. The SMS should also identify training needs for everyone involved and ensure the necessary competence is maintained.
Like all of these SMS things, it's mainly common sense and not rocket science....despite what the 'experts' would like us to believe about their field.