Storing Luggages

No one here can tell you that for sure. You will need to ask Hotel A. And also tell them how much luggage you'll have.

Email Hotel A to find out.

Perhaps look at 'open jaw' aka 'multi-city' air
Fly into one and out the other and not have to backtrack and have the issue of storing luggage.

I've stored luggage at a lot of hotels and never had a problem, but I've seen many hotels where the luggage-storage area either wasn't kept locked or ran out of space so overflow luggage was not in a protected area. This hasn't really made me nervous because my luggage is, and looks, cheap. I figure my suitcase is not the one someone is likely to take. But in my experience you cannot be sure how your luggage is going to be stored until you go to the front desk to drop it off. I imagine your odds of secure storage are better if you're staying at a 4-star or 5-star hotel, but I observed an exception to that assumption in the US a few years ago.

RadicalStorage.com
Worked for us.

the only way to be certain is to explain to hotel A what is happening and ask.