Cut out in assembly without modifying the parts

Good morning,

I need a suggestion about how to proceed with some assemblies. We use Creo 2.0.

I have an assembly where I have at least two parts (part_1 and part_2) interpenetreting each other: it is a mistake, a choice made by the original draftman to save time that causes a lot of problems with hatching on the drawing.

I'd like to perform a boolean operation in the assembly removing the exceeding volume from part_1 using part_2 (see the attachment: the volume with the green outline inside the parallelepiped must be removed) but, and here's the trick, I don't want to bring any modification to the parts themselves: I'd like to keep the parts unmodified. Why? Because they are standard parts and they are released in PDMLink and the process of reviewing them is time consuming.

As you can see in the picture, there is a "cut out" feature in the model tree of part_1 (result of a component operation) but this means that this part has been modified.

I don't know If I explained correctly my problem: the only way I see at the moment is to create some "extrude" ore "revolve" feature in the assembly to remove the material without propagating the modification to the parts.

Thanks a lot for any feedback.

Have a nice day.