Well, long story short..
you have your moneysite, let's call it Domain A and you have 2 other domains B and C.
Domain B is newly registered and never been used before so it has 0 links pointing to it
Domain C is a 4 y/o domain with diverse link profile and a couple of strong links.
You can use both domain B and C as a 301 to help you rank your MS. There are a lot of different approaches to this, but the most common scheme is this one:
Because domain C has pretty strong link profile you really don't need to build any new links to it for now. Simply go ahead and 301 it to domain A from the registrar or via the htaccess (you need to have an active site for htaccess). All those juicy links will now point to your domain A which will give it a solid ranking/authority boost (boost will be bigger if domain C backlinks are relevant to the domain A).
Registrar 301 usually takes 3-4 weeks to take effect, htaccess 1-3 weeks but you need to rebuild the site first for this method to work.
Domain B is fresh and you can use it as a buffer for your spam and sape links. Go ahead and buy some quality sape/spam and point it directly to domain B. You can 301 domain B to domain A instantly or you can build a small site and wait a couple of days for links to settle and let the domain B index. You can use same principles from the first example (registrar/htaccess)
This way if your domain A gets penalized, you simply create new site (domain D) and 301 domains B and C to it. You can even do some other crazy shit but i can't talk about that publicly xD