In the situation by Meen, if you mean, I am the meen, I would have fought with you for not including me in the group
Ena matum othukeetinga, and with my sister Rajni, I would launch a serious of sibling attacks for excluding me from the group, the only redemption is if she tells me all the gossips.
On a serious note, I dont see anyone at fault here. Conflict resolution course la padicha oru vishyam ena na, there is nothing 100% right or 100% wrong. If someone is angry or is being ridiculous, we should try to see motivation behind it.
Like Meen being angry at Goodie, could be because of her genuine concern for her sister. She cannot go shout at Mask, or others in group, and Rajni is her sister, obvioulsy she wouldnt listen. Deep down, she knows it is not Goodie's fault or her say to not add her in the group. Even if Goodie had said no, Rajni may have asked others in group.
Rajni if she had blamed Goodie after asking to be added in the group, could be simply because she doesnt want her sister to hate her.
Goodie if she added Rajni to the group without thinking too much about consequences, could be because she trusts Rajni more than Meen trusts Rajni.
In the end, all had their reasons, the question is do you want to understand why they did what they did and move one or break away from them, is entirely up to each one of them.