So long you and your dad agree to whatever you do, it is legal. Legally, you are a 100% bene for the joint account, unless your dad dispute that those are your mum's monies which she does not intend to "gift" it to you.Understand your point of going thru the proper legal process.
I’m here to seek for a simpler alternative esp in my case , there will never be a dispute between my dad and I on who shd get the monies . I’m totally fine to close this ac and open another joint account wif my dad
You and your dad as the final legal say, always better to settle within the family than invoke the law to settle possible family disputes. Dun follow the book blindly, so long you are not like the Lee Family!