If the part plan is a sheet in the assembly plan it is possible, otherwise without PDM tools that will manage it in separate files I don't think it is available.
Thanks @Coyote, but I tried to put the asm in another sheet with the bill of materials, but I don't see how to retrieve the item number in the part sheet
This is what I usually do, I have a "Part Number" property that I use instead of "Item Number". But I wanted to know more about the possibilities of the latter.