Hi! Welcome to YT!! It doesn't surprise me one little bit that this little girl has you wrapped around her little paw. It is one of the best things they do, make their humans to fall totally, madly in love with them.
Two things come to mind when I read your post. First, at 6 months of age, she is very likely teething. Gracie Ruth had a lot of trouble eating her kibble when she was teething. I didn't want to change the texture by adding water or change to can food because sometimes is can be difficult to get them back to plain kibble. So I put some in a sandwich bag and cracked it with a hammer. G was able to eat the cracked kibble and once she was done teething continued on with it whole again with no issues.
The second thing is that you may actually want to look into getting a boy instead of a second girl. Sometimes there are problems when both dogs are of the same sex. Also, many people say that boys are more cuddly then girls. I can only say what I've seen with the 4 we've had. Annie was absolutely a momma's girl, although she loved her daddy, I was the one she sought out. But I had Annie before DH came into the picture and I think that has a lot to do with it. Boo & Yogi are both very cuddly, Gracie has grown into it. There was never an issue between Boo and Gracie, however, Boo does seem to have more trouble tolerating Yogi.
Of course each dog is different and many have same sexes that get along just great, and have girls that are just as cuddly as the boys. I'm just offering what I've seen with ours.
Good Luck and please let us know what happens with Minnie and how it goes with your addition.