I don't understand how to construct a specific connection on united.com. I have an e-cert that I want to apply to MIA-ORD-SFO with an overnight (<23-hr) in ORD. united.com wants to construct more "optimal" connections and applies my e-cert to the aggregate fare. If I do it as a multi-leg, the e-cert doesn't apply. If I do 2 one-ways, it applies against one and not the other.

Can I construct a specific connection to do what I want?

Thanks.