Co ownership flat sale query

A flat in co ownership between mother and son, which they want to sell. 
Want to know if this money should be taken / transferred to a joint account or it can be taken only in son's name? 

Also, if the fund from this sale are to be reinvested in a new flat already shortlisted (intended to be bought in the son's name alone) do the fund still need to be transferred to a capital gains account till the agreement stuff is done for the new purchase or it can be transferred to a normal savings account and then transferred to the property developer.