Srinagar: Jammu and Kashmir Chief Minister Omar Abdullah on Saturday said the euphoria in BJP over roping in Prime Minister Manmohan Singh`s "unknown" brother Daljit Singh Kohli showed mind-boggling logic at work. "The PM weakens the UPA, yet somehow we are to believe that his unknown brother will strengthen BJP. Mind-boggling logic at work here!" Omar wrote on micro-blogging site twitter.Com. Referring to BJP`s criticism of Singh as a weak Prime Minister, Omar said the national opposition party cannot have it both ways. "The BJP goes to town calling the PM irrelevant, yet makes a song & dance of his brother joining them. How can they have it both ways?" he questioned. Singh`s half-brother, Daljit Singh Kohli, yesterday joined BJP in the presence of its prime ministerial candidate Narendra Modi.