I think there are multiple ways of handling this situation without permanently losing your fish if some club members willing to lend a helping hands by temporarily adopting the fish from you and keep it for two years. after two years, you can take it back and restock them with your new pond. if you fail to build a pond after two years, then they can keep the fish or it's their choice to give it back or keep it. I think it's a fair approach.
how many fish do you have and how big are they? I can take care one fish for you until you build your new pond, then you can have it back. no time limit in this case. I will try my best to grow it and keep it alive but if it dies, it's no one's fault.
Steve