Hi! So I have 3 Autumn Spirit Ferrikkis from the brews. But, two of them are boys, and only one girl. Looking for anyone to Gender Swap one of the boys to a girl for me. Preferably free, but fine, I'll pay gold if necessary

Hi, just to let you know, on average on the Trade Broker, the Philter of Genderswap sells for around 210,000 gold(Though there is one selling for 200k at the moment), and sells for 100 diamonds in the Diamond Shop.
There are also no infinite kits for Genderswapping on the site like there are for genetic testing and making pets infertile, they're only sold as individual philters.
I wouldn't rule out the possibility of someone offering one for free, but in case you were to need to pay gold, here are some guides that may assist you in making gold a bit easier:

Lehana's Guide to Making Gold:
https://www.sylestia.com/forums/?thread=2280

Hundenelsker's Guide to Mission Pets and Missions:
https://www.sylestia.com/forums/?thread=12841

Snowdrop's Guide to Making Thousands of Gold in Minutes:
https://www.sylestia.com/forums/?thread=93706

I wish you the best of luck in attaining a Philter of Genderswapping though!

Though, another possible way to attain another girl is to see if anyone would be willing to swap/trade one of their girls for one of your boys. Posting in the Pet Marketplace if you choose to do this, would likely bring the most attention to your post.

If you were to choose this method, I'd be happy to genetic test your boys(That way you can see if they have any hidden or carried traits), before you make a trade, to see if there's one boy you'd prefer keeping over the other.
Brew pets can occasionally have hidden traits, even without a hidden trait being added during brewing, and will have a carried trait if the pet got both bonuses while it was being brewed(Excluding Majestics, both their bonuses give stat boosts).
Hidden traits are more recessive traits that are hidden underneath a visible dominant trait, they show up as purple after a pet has been tested. Carried traits can only be seen when a pet is tested and show up as green.
Here's a pet that displays hidden traits and carried traits:
https://www.sylestia.com/view/pets/?petid=7376941

You can see he has the visible traits:
Gene One: (MM) Ghost Shroud
Gene Two: (BC) Nature Runes
Mutation Three: (CC) Bone Mask

And since he was tested, you can see he has a hidden trait in Gene Two:

Gene Two: (BC) Nature Runes - Hidden Trait Floral Design
The second letter before the trait name (The C out of the (BC) ) indicates what the hidden trait is. The first letter indicates the dominant/visible trait.
The Generator is a wonderful reference for checking this.

You can also see his carried traits:

Gene Three: (ND) Diamonds
Mutation One: (NC) Glowing Mushrooms
Mutation Two: (NF) Fae Dust

For me to genetically test your pets, you'd set them to my user ID for 1 gold(Make sure to put in my user ID in the Sell to User ID box, or else they'd be set for public sale, which could lead to another user buying them), then I'd buy them, test them, then set them to your user ID for 1 gold for you to buy back.
If you'd rather me not test them though, that's totally okay too, I just wanted to offer. ^-^

And apologies if I went a little overboard with explaining, I always try to attempt my best to make sure I explain what I'm talking about thoroughly.

I am aware of how Genetic Testing works. I did not realize they sold them in the Diamond Shop, so once they are are both adults/adolescents to see which I like better as a male, then I will genderswap them. Thanks!