"Onlyu" is supposed to be a pun on "yu". The "り" in "ひとりっこ" here was replaced with a "ゆ" which seems to be one of the types of things yukkuri say to be just slightly more annoying.
Of course!
When I come back wif you, Mamwa is going to be so surprised!Yuyu!?
Are you sure?Hey Shanae!
I cwame up with a bit of an idea...Could it be... A miracle from God to the Reimyu who lost her accessory...!?If you'd like, would you like to stay with Awish's house?
Awish is an onlyu child, so I'm sure Mamwa will welcome you too❤︎Yupi!
W-whach?