In house recommendations

IDK what you mean by in house recs because you are actually talking about two completely different things. An official rec from an alum merely checks a perfunctory box, and can keep you from getting cut for not having one if it comes down to that kind of chapter decision, so yes, do get your recs. It shows that you are interested in the chapter and cared enough to go to the trouble of securing one, but a rec will never, ever, secure a bid or even an invitation to the next round. On the other hand, the actives you already know can really be an advantage for you - IF they like you enough to speak up for you enthusiastically, and IF they have the influence and respect in their chapter for their opinion to hold sway. It's a chapter decision so there are all kinds of dynamics in play, but yes, you are right in letting them know ahead of time that you will be coming through. Good luck.