Will the iKQ MCB's and RCBO's fit the older KQ distribution board? are they cross compatible?

Yes, both the iKQ MCB's and RCBO's will fit the older KQ+ and KQII  single phase and three phase distribution boards these are cross compatible.

The new replacement of Kq10C132 MCB = SE10C132
The new replacement of Kqe132c03 RCBO = SEE132C03

Released for:Schneider Electric Ireland