Shimaidon

BUR #60717 has been rejected.

create implication brother_and_sister_threesome -> shimaidon_(sex)

Subset.

The shimaidon wiki says:

Group sex with two (or more) sisters.

And the brother and sister threesome doesn't specify at all who the third person is, so there's only a limited set of those images which are shimaidon where the third is also the pair's sister.
Look at post #10908078. It shouldn't be tagged shimaidon, of course.

Edit: Actually, it looks like brother and sister threesome specifically says that the third is not related to them, so it's never shimaidon.

user_781002_is_gone said in forum #443889:

BUR #60717 has been rejected.

create implication brother_and_sister_threesome -> shimaidon_(sex)

Subset.

The brother and sister threesome wiki would indicate this is not a subset of shimaidon (sex). 1) The wiki defines the tag as a brother and sister having a threesome with an unrelated 3rd party and 2) even if that is changed, the tag would still be applicable to MMF threesomes.

The bulk update request #60717 (forum #443889) has been rejected by @nonamethanks.