Originally Posted by GUWonder

If you are allowed by BA@CDG to gate-check the stroller at CDG, then you can and should ask at CDG (and definitely confirm at the flight gate) for the stroller to be set for gate-delivery at LHR if you want it at LHR.

If you check in the stroller at BA's check-in counter at CDG, the stroller will likely be tagged to MIA with no need to claim it at LHR. Check your claim tag in that case to make sure it says MIA (and LHR for a CDG-MIA-LHR routing) and that there is nothing about "gate-delivery" on the claim check, check-in tag for the stroller, or otherwise.

If you want to gate check in the stroller and have the stroller tagged for delivery at MIA baggage claim (but not tagged for delivery at LHR), there is a risk of a mess up unless and until you're given a claim check of sort that mentions that the bag is to be delivered at MIA. In such case, make sure it has no gate-delivery tag/instructions on the tag/stroller, or there could be the unfortunate problem of the stroller being gate-delivered at LHR and you not knowing about that until it's too late.