Gift deed for proof of funds

Hi my brother and his wife have recently been invited to apply to settle using the Canada PNP programme. Part of the application is they have to show funds that they have access to support themselves. So to fulfill this requirement I transferred the whole amount to them as gift in end of May. So just short of 6 months as their deadline for applying is early November so they wont have full 6 months bank statements from when the transfer was made.
So the agent has advised that since they haven't had the money for full 6 months in their account, they need a gift deed from me (based in the UK) saying I am gifting the money and they can use it anyway and I wont ask for it back etc.

Can anyone advise if this is correct. Do we need this deed? also where can I get one from as it has to be notarised I believe.

Thanks