How to add custom alt and title for each image from multiple property?

Question

1C-Bitrix

Products have dozens of images in the multiple file type property, and each of them needs to be given a unique alt and title. But how to prescribe them for each picture, there are no such fields there, there is a description field, but it is used for other purposes. I'm in stupor. By default, the name of the element was written there.