The Diana bag is gorgeous. I recently bought one with intention to use it for dinners and fancy parties. So it will not so much use but it will be there to use until I am very very old
, it is such a classic looking bag with great quality. I would not sell my Diana bag to fund another bag. I would instead try to save up enough money to buy the other bag.
With that being said, everyone is different and I do think you should use your bags. If you never use it today and you think you wouldn’t regret selling the bag - well then I definitely think you should sell it.
If you afraid of the lambskin I don’t think you should buy another lambskin bag, especially since I think the vintage lambskin bags are much more durable than the recent lambskin ones.