Mother selling land and buying another land, family members contribution.

Mother sold land bought in 1999 at a gain of 15,08,000 in 2022. The amount is placed in a capital gains account for exemption from capital gains. Assumption: it can used only for construction in the next 3 years or buying house in next two years under 54F. Intends to use it fully for construction from April 2023 till Dec 2023. Now, mother is buying land for Rs. 13,50,000 consideration price. She has Rs. ~ 7,60,000 in her account (so will issue a cheque for the seller). Should I or father or both transfer the remaining amount Rs. ~ 5,90,000 to her account, if yes, then how (as in normal transfer, gift, loan etc)(minimising her tax liability) ? Or can I or father or both transfer the remaining amount to the seller by RTGS / NEFT / cheque etc? Not sure if the whole amount has to be transferred from buyer to seller or buyers family members can contribute as well. (The land will be in mother's name only). Mother's primary source of income is tution and interest income (has been filling form G till date). This will be the first time her filing an ITR. Please suggest how she can reduce her tax liability and how to show the capital gains in the itr to be filed.