yes it should, diclofenac is poorly soluble, eventually you can acidified the water with lemon or something since codeine is a base and diclofenac an acid
Yes, it is possible. Diclofenac has poor water solubility (2.37mg/1000mL at room temperature). As noted above, be sure the water is below pH 7 or else the diclofenac will become much more soluble.