You can send the money, however, the tax indications/legality depends upon your relation and amount.

Resident Indians can send up to $250,000 per year to their relatives abroad for certain expenses, including select investments.

Transfer the funds via NRI account 

You can send/gift up to USD 2,50,000 per Financial Year (FY) for maintenance of close relatives abroad.

No tax implications.

There is no legal bar to send money abroad as long as you keep official record of the lawful source of money.

If the money is sent from abroad then there is restriction on certain conditions.

If that amount is taxable in your return then you don't have to pay any tax but you need to pay remittance for sending it

Yes you can send money and give it as a gift for saving tax.

Give it as a gift to your sister.

An amount of  $250,000 per year can be sent to relatives abroad , there wont be any tax liability on you.

Yes it is legal.

You can send said sum of money to your sister in order to support her maintenance.  No tax implication.

There are no restrictions on the frequency of remittances under LRS. However, the total amount of foreign exchange purchased from or remitted through, all sources in India during a financial year should be within the cumulative limit of USD 2,50,000

A resident Indian can send money to the UK for the maintenance expense of their close relatives up to up-to USD 2,50,000 per Financial Year (April - March) ['relative' as defined in Section 2(77) of the Companies Act, 2013] abroad.

FEMA covers all forms of foreign exchange transactions and remittance payments. That means that there are guidelines and rules which apply if you’re an individual wanting to move money in or out of India.

The part of FEMA which covers outward remittances for Indian citizens is called the Liberalised Remittance Scheme, usually shortened to LRS.

Under the LRS, Indian citizens can transfer money to bank accounts abroad without needing to get special permission. However, money can only be intended for a set number of purposes, and remittances are allowed only up to a maximum annual limit which is currently set at USD 250,000

Under the LRS, Indian citizens can transfer money to bank accounts abroad without needing to get special permission. However, money can only be intended for a set number of purposes, and remittances are allowed only up to a maximum annual limit which is currently set at USD 250,000.

In broad terms, the LRS allows Indian citizens to transfer money abroad for the following purposes:2

• To cover the costs of overseas education and living expenses for students living abroad
• Travel and tourism costs, as well as business travel expenses
• Medical treatment abroad
• Purchase of shares or property overseas
• Supporting family members living abroad
• Gifts and donations - it’s worth noting that some organisations don’t qualify under LRS rules

To remit over USD 250,000 in one year you’ll need special permission from the RBI, and you can’t remit money which originates from certain sources including.

1. Yes it is legal to send money to your sister through remittance.

2. There will be no tax implication for your sister as she is your blood relative and you have paid taxes on income in India.