UK Visitor - Available Funds Proof

Dear Experts,

I am applying for a visitor visa for my in-laws, whose details are:
Father-in-law - Supporting himself, retired and get pension
Mother-in-law - Sponsored by her husband(my father-in-law, travelling together), housewife dependent on husband.

In their individual application form, I mentioned that they both plan to spend £2000 for their trip.

Documents as Proof:
Pension proof: 6 months statement showing pension and balance is around £1900(in equivalent INR)
Fixed Deposits: Two fixed deposits of £21,000(in equivalent INR) each under the joint names.

Issue:
Although I have shown funds of £42,000(from retirement benefits) in fixed deposits but the bank statement has only balance of £1900.
The expenses planned are (£2000 + £2000). Can this be an issue? Should I wait for their bank statement balance to grow or would FD serve the purpose?
Please help.