When Brian asked Whitney to marry him, he knew he would not only be marrying her, but accepting her daughter, Brielle (Breezy), into his life as well. During their wedding, they recite their personalized vows to each other, and then Brian turned to his soon to be step-daughter and presented her with another set of vows just for her. The significance of that gesture is one that will be remembered by mother and daughter for years to come. The moment he is sparing on his wedding day for a little girl who may never remember the specific words said to her is one that will never really be forgotten.
Merging two families can be difficult, but if this moment is any indication, Brian has been handling it wonderfully. The American Psychological Association provides a lot of insight and suggestions on how to handle this delicate situation so everyone involved can come out happy. Since Brielle appears to be under the age of 10, she shouldn't have many issues accept a new adult into her life, but it is good to keep age in mind in how you handle this. 

Kids that are older than 15 should handle it well since they aren't relying on much parenting on this point, but it is still good to not just assume a parental authority. It is when they are between 10 and 15 that you would need to be the most careful as they still rely heavily on their parents, and a big change can have a lasting effect on them if it isn't handled well. The overall consensus is you don't want to just jump in and place yourself in their dad's (or mom's) shoes. It can come across as too strong and invasive and make a child feel like they are being replaced.  It's more beneficial to step in as a friend and work your way up to a more personal relationship. 

It looks like Whitney, Brian, and Brielle are off to an amazing start. It is hard to watch them give their vows to each other, and Brielle, without getting just a little bit teary eyed. Check it out to hear all the sweet promises he has for his new wife and step-daughter.