erm, this para contains some inaccurate info...
1) You can cash top up any amount you like in your own SA, until your SA hits FRS. But only the first 7k gets tax relief. Seriously, if you are super cash rich, you can one-shot pump your SA until it reaches 171k if you like
2) You can similarly do cash top up to the SA of anyone you like, doesn't have to be a family member even. But only top up for: parents, parents-in-law, grandparents, grandparents-in-law, spouse and siblings; are eligible for tax relief. And for spouse and siblings tax relief, they have to have annual income less than 4k
3) There is no limit to OA. I don't know any way to "funnel" OA to SA, except through self-initiated CPF transfer
4) The part about there being no limit to SA is correct though