Housing loan rebate claim by Wife

 I have two properties in Joint names with my wife, Wife is also the co-borrower of loan in both properties.

1. EMIs are being paid from my salary but joint account. There are no other sources of income in this account. Only credit of salary and official tour expense reimbursements.

2. Wife's salary is not accumulated in this account. She has separate salary account where I am joint holder.

3. There was no agreement of sharing the loan burden between us at the time of taking loan.

Can she also claim rebate of housing loan (Principle or interest), How, and what percentage should she claim.