I think the only way you can achieve this by calculating the number of supported by in SR Type Field and pass that as a qualification to approval chain.
You can use form "AST:AssetPeople_localized" and filter down the record based on CI and Support Group.
Once you able to get the count, you can build your chain by following document @ The Pulse: SRM Approval Chains and Implementing SRM Approvals based on a Users Response to a Question
Hope this helps
Can I create WO dynamically on basis of how many "Supported By" relationship exists for a CI. Its same concept as for approval but I want to create WOs dynamically.