Replace vanilla police cars...

first off dlc packs only allow you to use those vehicles, (not peds/ai) So when I call backup, the basic vanilla cop cars dont show up. People say you can use ultimate backup and fix this. They also say when using LSPDFR you can go into your lspdfr settings and under agencies, change it to where dlc cars will respond for backup... However sometimes I dont want to run the LSPDFR plugin, but still want the cop cars... Basically what im looking for is a way to make dlc police cars replace the basic vehicles in the game without using extra mods or plugins. Is there an agency file already in gta? surely there has to be something right? How else do the police cars spawn in the correct locations? If anyone could help me with this it would be greatly appreciated, thanks.