I understand, thanks for sharing ,
You only need to ensure your father does not wow the payout, this part is the part I am concern abt, sometimes he spend spend unknowingly....

I try to look at things at different angle from this issue/deadlock
Some of the best scenarios I can think of
1) Transfer my OA to my father OA...this one is the best, but I am not co-owner
(knn CPF dun allow this)
2) Top up my father OA DIRECTLY, so he can only use the amount for housing use directly. However I cannot just top up his OA account
(knn CPF dun allow this)
3) Use my father RA to pay from month housing loan, assuming I top up $400 to his RA every month, the HDB can deduct from that acc instead of OA, swee swee, I can earn some tax relief.
(knn HDB dun allow this)
4) Use my father MA to pay for housing loan, my father got
$50,000 in his MA for medical issue. if this can use half for his housing loan, then problem will be solved.
(knn CPF dun allow this)
5) Straightaway use my CPF OA to pay for the housing loan, I got stable income but I am not co-owner.
(knn CPF dun allow this)