Creating missing textures/surfaces

In the last few days, I've begun to understand the importance of having ALL the correct maps for my models when importing from Daz to Blender. However, some of the models I've purchased from outside of the Daz store are missing some textures. This means when I import the finished model into Blender, they don't have that "realistic" look that the others do. For example, I downloaded the Tommy and Joel Miller models from Patreon, but they only come with Diffuse maps for the entire body, and (if I remember correctly) a Normal Map for the head. Specular, Bump, and Normal I can probably substitute out for another one from my Daz library (Tommy looks really similar to Holt 8). The big one is the Subsurface Scattering. Is there a way to create one in an outside program using the Diffuse texture? I'm highly proficient in Photoshop, as that's where I got my start in the world of computerized art. I just need to know if it's possible, and if so, how to do it. Maybe desaturate the image by 50% and then add a pinkish tone or something. Any help would be appreciated!