Let her out for a little bit when you are there. Watch the other cattle. They will want to see who/what she is. Some might pick on her, then they might not. She will want to run after being kept in. The 2 yearlings may want to play with her. Since she is a bottle baby, she ought to come to you for feed/bottles etc. so you ought to be able to get her in without too many problems. If they don't pick on her, she will just follow along and then you can call her to come in for her bottle and lock her in at night for safety and peace of mind.....
One thing, you really need to get the bull separated from the 2 yearlings. They will be coming in heat and will get bred too young. Seriously, most of ours will be in heat by a year old..... my jerseys have come in heat as early as 6-7 months old. You don't want them to have a short first heat and get bred. I have one family of very fertile beef cows.... 2 of them were bred while still on their mothers, before we weaned them, and then didn't know they were pregnant until too late to abort them; and they calved at 18 and 19 months..... they did okay, and raised the calf, but they are smaller cows and will never get any bigger now. Luckily they did not have any problems calving. But it stunted them. A heifer at 10 months, that gets pregnant, cannot grow and feed a fetus, then calve and milk and feed a calf without it taking a toll on her. You cannot feed her enough to make up for the drain on her system. Once the growth has been stunted, you cannot reverse it. Then there is the possibility of them having trouble calving. I like herefords.... but they are known to have bigger heads and shoulders... so a bigger concern for a too young first calf heifer to be calving.
Run the bull with the steer, and even the pregnant cow til she calves, but you need to get him separate. I don't advise bulls for someone with less than 10-20 cows because he works for a month and then is a freeloader for the other 10-11 months. And they get wanderlust when there is nothing interesting to keep them home (cows coming in heat). Is there is anyone you can rent a bull from instead of owning one.....or can you rent him out so that he is not there looking for trouble to get into? Renting a bull can be tricky since there is possible problems with STD's in cattle.... but a bull getting out can be a real problem too.
He is a good looking bull, but as he gets sexually mature..... meaning in his prime, he might be a problem. The best dispositioned bull can still become a PITA if he decides to go galavanting "looking for love". I don't want you to be surprised down the road. Bulls are a WHOLE DIFFERENT BALLGAME than steers.