Spanish help to say "you may have.."?

"you may have.." like you could have included this... does this work: conditional+imp.subj? podria incluiera, or should it be condiitional+past? podria incluio, or pudiera incluio.........i'm so confused. please explain which it should be and then what the other ones would mean if they're incorrect. also, can you only use subjunctives if it's a 2nd clause? it seems that every sentence structure i learn with subj., it's the 2nd clause-it follows an already conjugated verb except for commands. include your credentials please! GRACIAS!