Housing loan

Yes, It can be claimed by both the co owner provided both have paid.

Inorder to claim deduction, the assessee should have the right over the property and it should be shown as a house property in Schedule HP of Income tax return.

It will be possible incase of joint owners taken loan jointly....

So, the loan should be in joint names...........or the property in joint names.....???

Both should be in the joint name.

The property should be a joint holding for sure and regarding the other, you have to consider the rationality.

I think one should pay his ones liability and not some or other relative. 

Will you agree that ones son has paid ones loan. What is his consideration when the liability is not on him. If so it has to be considered as  gift, nothing otherthan it.  Taxation has nothing to do with relations except with ownerships. 

But as law is silent about you can claim but with an ascertained risk of calling off by assessing officer for income escaping.

Property and Loan both should be in joint name.

In balance sheet also,propery(1/2) shall be shown in both the assessee.

Both can claim deduction of Rs.100000 if both are paying that much amount.

Another Issue:

Say, Loan and Property both are shown in father-son b.s., payment from bank is done only by father.Then, in that case,if the son is transfeering that much amount to fathers account, then only deduction will be available to son.