How old are these birds, in weeks?
They can possibly be injured if cockerel doesn't have good technique.
Multiple males can make them all behave at their worst...not sure if you have one or more.
What are your long term goals for keeping chickens?
Unless you want to hatch out more chicks in the future, you don't need any males.
The 'rooster' to hen ratio of 1:10 that is often cited is primarily for fertility efficiency in commercial breeding facilities.
It doesn't mean that if a cockbird has 10 hens that he won't abuse or over mate them.
Many breeders keep pairs, trios, quads, etc
It all depends on the temperaments of the cock and hens and sometimes housing provided.
Backyard flocks can achieve good fertility with a larger ratio.