My question is about an emotional feeling: Is there any limit regarding the relationship of brotherhood and love among siblings?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

Your question is actually unclear for us; however, if you mean with emotional feeling towards brothers and sisters the sexual inclination that afflicts some of those who have weak souls and are sexually inclined to males or to their female Mahrams (unmarriageable kin), then this is a devilish feeling that ends with immoralities and evildoing. It is not permissible to go too far in that regard; rather, it is obligatory to give it up, abhor it, and avoid the causes that lead to it.

Allaah Knows best.