Some of your friends and relatives may offer their services as a wedding gift. A musician may offer to play at your ceremony or someone who likes taking pictures may offer to be your wedding photographer or a baker in the family may offer to bake your wedding cake.
All of these offers are generous and can save you money, but you may want to think twice before accepting their offer to work your wedding.
Friends and relatives who have wedding-related hobbies are not wedding professionals and may not have enough experience working a wedding to deliver the service you require. Also, if they are a professional and your wedding is a freebie, they may cancel on you if they get a paying gig for the same day.
It's very important that if you do "hire" a friend or relative that you sit down with them well before the wedding and make sure that they understand exactly what services you require and that you understand exactly what services they can perform.
It's okay to say no thanks if someone does offer you their services. Just explain that you either already hired someone or that you wan them to be a guest at your wedding and enjoy time with family and friends.