INCOME TAX ON PROPERTY PURCHASE

hello everyone, hope you all are doing well.
actually my question is related to income tax . my uncle purchased a piece of land in nanital few years back, now he started construction on this land for resell purpose.
my uncle's brother also investing in this land but instead of direct investing from his account my broo uncle tranfer Monroe from my uncle's bank account for expenses of construction.
my my question is
1. how to treat this whole scenario in income tax
2 and does my uncle's brother and my uncle need any mutual agreement that the deposited money in my uncle's account belong to his brother , I mean how to prove that ,the money deposited in his account is not belong to his income it's actually a investment from his brother
please your answer will be appreciated.