Mixing Game Content

That is not possible if you wish to run on all player's machines that are running Half-Life 2: Deathmatch. This is because there is no guarantee that the person downloading your map has both installed Counter-Strike: Source and HL2DM installed. You are not required to have Counter-Strike: Source installed to run Half-Life 2: Deathmatch, for example. The reverse is also true. Therefore, a player running your map that didn't have CS:S installed would get an error because they didn't have the required model or material.