No you cannot transfer fat from one person to another person.
Fat cannot be transferred from one person to another person because the persons body would reject that fat that was transferred to them.
You can transfer fat from your own body from one part of your body to another part of your body.
But if you want to increase your weight then all you can really do is increase your calorie intake by eating more food and taking weight increase supplements.
You can also take weight increase injections but they are not cheap when done at a doctors office.
You might be able to take weight increase injections at home as well.
That would be a cheaper alternative to having the doctors give you weight increase injections.