Question about nomination of flat in coop society (mumbai)

Under bye law 32, my society has asked me to furnish a nominee for my flat in the cooperative society. Is nomination mandatory EVEN if the flat is co-owned ? In my case, my spouse and me re joint holders in the sale agreement and in the society share certificate? Can we nominate each other (like banks have an either/or survivor operation) for now? Thanks for any advice on this