SPA for Selling and Buying

Hello,
I would like to ask what kind of SPA do i have to send to my sister as she is my attorney-in-fact or representative to do all necessary documents to sell and transfer a land title to my name?
We have a family land, so i sent here the SPA to sell our land since its needed an extra-judicial settle (all siblings has to sign). But one title of our family land needs to be transferred to my name alone since i bought it from them. Do i need another SPA for that, because one of the titles need to be transferred under my name, but all of my sibling still has to sign.
Also, how  many hectares are allowed to name under one person? Can a property named to my underage kid and put me as administrator?

Please help! Thank you in advance.

It can be specified on the deed of extrajudicial settlement itself that the portion is being adjudicated only to you. Alternatively, the deed of extrajudicial settlement may also contain all the other heirs' waiver over that portion of the property in your favor. You don't need to execute a separate document just for that, so don't worry about executing another SPA because you don't need to enter into another transaction. https://www.alburovillanueva.com/land-titles-real-property-registration

Good PM! Would like to inquire if I can deal (sign Deed of Sale) with the brother of the lot owner who was given an SPA however the SPA issued to him was only from the wife and not with her husband?

Additional background... the property is named to Mrs. X (Filipino) married to Mr Y (Japanese).