Custom forms - multiple upload fields / individual field type

Description - To be able to have an upload field related to a topic in a custom form, it would be helpful to have an upload field as a custom field type.

Why is this feature important to you - We have several briefing forms, which require to be able to upload documents related to different fields included in the form.

How would you like the feature to work - Being able to add an upload field at any position in a custom field. Perfect would be, to be able to define a target folder individually for each upload field.

Current Behaviour - We only have a single upload field at above or after a custom form. If the requestor has to upload different documents, he/she has to remember, all those to do it after / before filling the form completely.