Your sister who refuse to sell, did she give any reasons?

You already faced a roadblock, that's without Mr. passing which makes even more roadblock, in the end of the day the more people getting involved, the harder it is to sell.

I guess u may need to talk this out with her, and I truly understand communicating with people who do not want to talk about it is extremely difficult and stressful yet the responsibility still lies on you to make it work.

Sorry out of topic a bit, probably influenced by every time see Thanos comment about Malay selling land to Chinese to make big money contributed to this thinking partially I guess. May need to let her know it is not the same as narrated by Thanos, because this will only get more difficult end up no one getting anything from it in the future, equal to just throwing this land to a forever wasteland.