While I get why you want this, unfortunately I can't support because there's a reason that certain items can only be averaged. If they could be combined, it would lower not just their market value, but also the usefulness of high-level pets which are able to find g100 ingredients.

And on the contrary, averaging items can be used to raise the grade of items! It's just not as easy as combining. I believe someone wrote a guide about it, let me go find it. Ok, found: pixpet.net/forum.php?section=posts&t=1169&page=1&title=Forum---Game-Guides---Average-Grades-Tips--Tricks

Plus, a low-grade ingredient can still make a high-grade potion or evobar as long as your other ingredients are high-grade. Even at the refining stage you can get a high-grade stew as long as your sprouting pumpkin is g100.

Again, I absolutely get it. Being able to combine ingredients would make life easier. I just think it would make life too easy, and hurt the economy, and high-level pets. xP