Need Advice for 3 Adults + 1 Child

[3Aumillers]

We are all set to arrive on 10/1 at 3:55 p.m. arriving on American Airlines. Our problem is we would like to rent a car to get us from the airport to POP and back again on 10/8. That sounds simple enough but luggage for 3 Adults + 1 child in addition to a stroller (full size / not umbrella stroller) simply will not fit in a car unless we go with a full size car (probably won't fit) or minivan. We would like to keep our costs as low as possible. Do they allow you to use ME for luggage transportation / delivery only??? Should we send mother-in-law on ME with our luggage and just plan to meet her at the hotel???

Any suggestions.

Thanks