Yes, you can also tie a rakhi to your brother-in-law as Raksha Bandhan is not necessarily celebrated only between brothers and sisters. Those who do not have their own brothers can tie Rakhi to brother in law. Raksha Bandhan is celebrated between any two people as a bond of love, care and affection, not necessarily between brother and sister only. This year, strengthen the relationship with a Rakhi thread and make it more official.