How Multisignature Wallets are affected in case of a hard-fork? In an event of forking, are there any special circumstances involving multisig wallets? I am asking this because Coinbase says they do not support forks and multisig wallets?

Below is a quote from the Coinbase site:


  Multisig vaults were originally introduced as a way for customers to
  manage their private keys and control their own security while still
  using the Coinbase interface. However, as Bitcoin forks become more
  commonplace, the complexity of multisig vaults makes it infeasible to
  support multisig withdrawals for each additional forked asset.
No, multisig addresses are not special in any way that is effected by forks. They are just like any other output on the blockchain.

The reason it is hard for Coinbase is because they need to implement support for signing and creating transactions for those forks which requires significant engineering effort. It's the same reason that they don't support every fork in the normal Coinbase wallet - it is difficult to implement such support so they won't.