The bulk update request #6115 is pending approval.

create implication inflation (48565) -> expansion (30456)
create implication weight_gain (10577) -> expansion (30456)

Reason: Nobody replied to or gave their input to my post, so I'm going ahead, do a bur and hope for the best. https://e621.net/forum_topics/41864

To reiterate, right now if someone wants to see both inflation and fattening simultaneously with more than one artist tag that ain't possible, turning expansion into an umbrella tag would make this possible. Expansion is already used interchangeably with inflation anyway.

Other tags could be included like pregnancy.

Are all forms of weight gain necessarily expansion? I don't think I'd classify natural weight gain as expansion. As for expansion being synonymous with inflation, it doesn't seem like that to me. There's a lot of inflation within the expansion tag, but a bunch of other forms of expansion are included under it. Certainly, there are more images tagged expansion but not inflation than images tagged both. Pregnancy would be even more of an unusual inclusion. Expansion usually doesn't include natural biological growth.

Maybe there could be a different tag that combines the two? I don't know, but I don't think expansion works here.