Well, here's the second choice, by the way, a few things:

1- I originally planned for Flowey to stay in the Underground, but then it occurred to me that he should accompany Clover to the surface, now Clover is willing to help him, just as he did in the Underground, I also considered having Undyne take the throne from Ceroba, but then I thought: "Nah, that would be too cliché," so I decided to let Ceroba rule peacefully, at least now the Underground won't be hostile to Frisk when they fall

2- The Royal Guard still exists, but they no longer hunt humans, rather, they're more like a kind of police force for the Underground

3- Asriel was so devastated by Chara's death that he quickly fell into a deep depression, although Asgore tried to help him, he did everything he could to stay away from him, he did this to avoid directing his hatred and rage toward his own father and having him executed for regicide and treason

Unfortunately, Asriel would eventually lose the battle against depression, something Asgore himself would witness

4- Toriel tried to take Asriel with her, but she couldn't because Asgore wouldn't allow it

5- Because Clover absorbed Asgore's soul, he cannot rest in peace because he is linked to Clover's soul, unless he dies or expels Asgore's soul from his own

6- The human soul extract that Martlet gave Clover, which the latter injected, not only invigorated him but also increased his determination considerably, this means that Clover is now the one controlling the timeline, but Flowey is unaware of this, perhaps Clover will tell him at some point

7- Just like in the original UTY, Chujin is still the creator of Axis

8- When Integrity (Melissa) couldn't go out much because of the monsters and the Royal Guard, the Ketsukanes hired a nanny to take care of her,  and although she knew Mel was human, couldn't say anything because Chujin and Ceroba kept her under threat, the nanny's name was Betty

She stopped working as a nanny after Melissa's execution

Extra: Upon learning of Asgore's death, Toriel decided to leave the Ruins and move to Snowdin to overcome her madness from having been hidden there for so long (yes, Toriel is mad, but despite that, she still acts somewhat like her original counterpart)

Underfell Yellow: Neutral Route Ending (SECOND CHOICE)