Usually, the main contractor will provide the contract, but some subcontractors have their own agreements. If they do, you will need to agree on whether to use yours or theirs. It is not advisable to have two contracts in place as they may contradict each other, and should you ever have a legal dispute, it would be difficult to determine which contract had the most validity. If a subcontractor isn't happy with any of your terms, you can amend the terms or add special clauses for a bespoke agreement.