The Third Part needs to be an offer that will produce an ongoing income. This should add value to the client, your lead, and include an element of continuing training or service that you lead, which will help keep them continuing with the service or training.
There is a long list of products and services that might be offered, so having someone who been marketing for a long time is a great advantage. This is where someone, like Joel Theiren, makes a lot of sense to link up with.