Altium Schematic Library Ready for BOM
You can set any kind of property in the Schematic Library that you want.

You can even add a property "MyComponentType" and set those to 1, 2, 3, 4, ... etc.

You can then tell the BOM tool to group lines based on whatever property you want, (footprint, description) is normally the default pair if I'm not mistaken, so if you just add a MFG part number to the description of your components you will likely not even have to change anything in the BOM tool.

You should never replicate footprints just for component value, and Altium - for all its strange quirks - does not force you to either.



You can also set properties for the components in the Schematic directly, and I only mention this to tell you why you should avoid that if you can:
If you have one single Schematic Library component called "Capacitor" and set the manufacturer part-numbers individually in the schematic you will:


Have a lot more work than just have a 100nF, 1&mu;F, 2.2&mu;F in your library and place those where you need them.
Lose all that information when you change the library component and have the library update all schematic sheets.
Potentially cause an unmanageable mess if your project is medium to large.




You can also add properties directly on the board and use those in the same manner, but for that you have to consider the same three arguments as above and add the layer of mess and risk that results from having a disconnect between board and schematic.