Frequent flyer number is a unique number for each registered member and can only be used by him not any other person during reservation or checking.

No, your girlfriend cannot use your frequent flyer number for her own flight to earn miles. Airline loyalty programs are strictly personal, and the name on the ticket must match the name on the frequent flyer account. If she enters your number, the system will reject it, and no miles will be awarded for the trip. However, you can use your miles to book a flight for her. Most programs allow you to redeem your points for a ticket in someone else's name, essentially gifting her the trip. In 2026, some international airlines (like Emirates or British Airways) offer "Family/Household Accounts" that allow you to pool miles from multiple people into one balance, but even in these cases, each person must still have their own unique membership number to track their individual travel history.

That’s an excellent question, and the answer is a bit nuanced: It depends entirely on the airline’s specific rules, but generally, no, she cannot simply use your number for her flights.

Here’s a detailed breakdown of the key points:

The General Rule: No

Frequent flyer accounts are non-transferable and for individual use only. The cardinal rule is: Miles/Points are earned by the person whose name is on the ticket. If your girlfriend books a flight in her name, she must credit the miles to her own frequent flyer account (with that airline or a partner). She cannot add your number to her reservation to earn miles for you. This is considered a violation of program terms and can lead to forfeiture of miles or even account closure if discovered.

When It Might Be Possible (The Exceptions)

There are a few specific scenarios where your number could be involved:

1. Booking a Ticket for You (As a Gift): If you are the one flying, she can certainly book the ticket for you using your frequent flyer number. The name on the ticket must match the name on the account.

2. Family Pooling or Sharing (Specific Programs): A handful of airlines (more common outside the US, like some European and Asian carriers) offer “family pooling” or “household accounts.” This allows designated family members (sometimes including domestic partners) to pool their earned miles into a single account. You would need to check if your airline has this feature and if your relationship qualifies.

3. Transferring Miles (Often for a Fee): After she earns miles in her own account, many programs allow you to transfer miles between accounts. However, this almost always comes with significant fees and restrictions (e.g., a minimum transfer amount, high cost per mile).