LTCG on sale of plot for joint owners

In your case you got 2 options

1. U/s 54 EC amount invested in the specified bonds issued by REC or NABARD can be claimed as exemption for LTCG.They should be invested within 6 months of transfer to claim exemption.

2.U/s 54 F within a period of 1 year before or 2 years after the date of transfer, a residential house is to be  purchased or within a period of 3 years after the date of transfer a residential house is to be constructed.

The cost of new residential house or LTCG whichever is lower is exempt from tax.

So simply purchasing a plot is not enough to get exemption.

If you purchase/sell any property in joint names, the percentage of share is considered.

For claiming exemption there is no restriction to invest own funds.

Thats your convenience, you can invest even debt funds.