Can you check a bag halfway through a journey e.g. leave airport to landside during a long layover?

My wife and I have a flight on Sunday from DUB to EWR via LHR.
Aer Lingus flight first, and then BA second. Economy first, business second. 4h 30m layover to get from t2 to t5. All one reservation.

We are visiting DUB as a separate trip to see friends first as a separate reservation, with lots of bag allowance.

We want to avoid:
1)lugging our luggage into and around Dublin (2 32kg bags, 1 normal checked bag, 3 personal items).
2) risking Aer Lingus checking personal items thru (they have a v weirdcarry on policy of having to check your carry on...)
3) relying on Heathrow ground staff to get all our bags across in time.

To avoid this we are thinking of asking family to meet us at T5 LHR and we drop most of the bags off there at bag drop off after transiting landside

Are we allowed to drop bags off half way through the journey for the last segment?