Babys last name

So my boyfriend approached me and suggested that I put him on the babys birth certificate and give the baby his last name...he is not the biological father, as i had met him after I found out that i was pregnant- and the father is in NO way involved or interested in being in the babys life, so i refuse to put the bio dad on the birth certificate regardless (we have a 2 yr old daughter who he has never met as well). I was pleasantly surprised by his suggestion...my man has 4 boys already, whom ive grown to love as mine.. i have NO doubt in my mind that my man has thought this through and is ready to take on this new chapter! Should I go for it?