Need some help with weld rotations and math?

Kind of an advanced math question here but I need some help.

https://media.discordapp.net/attachments/451797112095506435/480573566610309131/Capture.PNG?width=821&height=462

Using this crude ms paint as an example the rectangle is the player's screen. C is a block in the center of the screen. S is a block welded to C. In order to get S to center screen I've been moving C left by [c.X-s.X] and up by [c.Y-s.Y].

The issue is now the whole system is rotated -45 degrees and I still need a way to get S to center expressed in terms of C.

(The slightly transparent one is the new rotation)

https://cdn.discordapp.com/attachments/451797112095506435/480574844057026570/Capture.PNG

Don't measure it and tell me how many inches I need to move it, I need in terms of C and S