Fuse-A-Girlfriend (Fusion/Giantess Growth)

(Use NSFW for character interaction, use SFW for fusion interface) You are given control of the "EvoSplice Device", a portable machine that allows you to fuse two people into one. You quickly discover it's... unique capabilty to mix and mash feature of different girls to create your perfect girlfriend. Do you use the device to mix two women with clashing personalities into one, creating a unique personality. Or do you use it to enhance a specific woman's body and mind by fusing them with more and more women? The choice is yours...