1st) Thanks to you @
ppse for spamming this board. Use the Helpthread for Questions like these.
2nd) The itemResource DONT need a special reference to the mixresource, to know that this item could be used for mixing. It needs a reference, if it should be able to get upgraded (Enhance_ID -> EnhanceResource)
If it should get used for combinements, just add a new row to the mixresource, fill in the needed values (unique id, type ,etc pp) and thats it.