my relative they visit India frequently and after 6 months they will bring her back with themselves
She can't bring a domestic worker from outside the EU, back to the UK with her.
What you want to do can't be done anymore as the UK stopped that over 3 years ago.
Even if she could (which your relative can't) she must pay them the hourly rate of the UK national minimum wage for that 6 months (presently £6.50 and hour),
and pay all of their NHS bills (if they needed to use it).
It will be cheaper for your relative to employ an EU citizen for 24 hours a week (pay them £156 for 24 hours a week) as that EU citizen will then be able to get the UK to pay their NHS bills and they will be able to look for a second part time job to survive on.