You're having so much frustration! Rental emergencies and Infants/Toddlers and uncooperative grandparents. I totally sympathise but, if you take a step back, it's quite funny. We do this for fun? Roflol.
The ignored/hurt child thing is really hard to remedy once they've got it. I think they get it at the drop of a hat if they once see their parent attending to another. The only way to avoid it would be to keep them in separate rooms - not very practical or true to life. Repeated affection and apologies when available does make it go away eventually.
On Reddit, a few simmers also recommend apologizing to the Ignored/Hurt toddler, but I'm pretty sure sims don't have the Apologize option for toddlers, only Affection/Soothe.
Though toddlers have the Deep Thoughts option (for Ask Why and Ask About World), I see no Deep Thoughts option toward toddlers for children and older.
Chai has scoured all his social menus, but has never seen the Apologize option with Jing. (I've only had parents Apologize to children, not toddlers, before.)
In Jing's case, she gets it whenever she notices Chai interacting with the infant Bulan. Chai tried repeated Affection socials which Jing often rejects.
It's impossible to hide because Bulan's playmat is in front of the fireplace in the living room (as had been the case for the twins).
I do appreciate your suggestion about keeping Jing and Bulan separate.
It's not entirely possible, but I should've moved the tub so it didn't require passing through Bulan's nursery then locked Jing out of the nursery.
It's curious that Jing feels ignored but her twin Kamala doesn't. I'm hoping Jing will outgrow it on her child birthday. *crosses fingers
Complaining about Papa Surya is simply part of the story since Decha is an exemplary grandpa though he's not Family Oriented like Surya.
With Minsung working, it hasn't been easy for Chai to raise 4 kids in three different life stages.
I'm going to ignore Jing from now on. She doesn't deserve all the attention she craves. LOL!
Not gonna lie! All the recent glitches have been quite annoying, too!