If she's only 10 weeks of age, I'm surprised Boomer reacted as he did. Typically adult rabbits will accept baby rabbits ---as long as they are babies. Once hormones kick in, it's a whole different story.
Honestly, starting with a baby is a very tough (and risky) way to try to find a bondmate. It's tough because they should be kept apart (where they can't reach through an ex-pen) until after she has healed from being spayed. Of course she can't be spayed for awhile. Five to six months of age is usually when females are spayed BUT with flemish, it is usually later than that because they are considered juveniles for longer due to their size. So they should be kept apart for the next several months.
It is risky because once you've waited out all those months until she can get spayed, then allow her time to heal, it won't be until after all of that that they can be introduced and see if they have the potential to accept each other. They may. They may not. But unfortunately, if they don't get along, you've already invested all that time, money and effort. That's the risky part.
Since Boomer already had a negative reaction to even a baby rabbit being in his space, that doesn't bode well for future bonding. He may be one of those particularly choosey rabbits that will be quite particular about what rabbit he will accept as a bondmate. If this is indeed the case, then the way to increase the chance of finding a compatible bondmate would be to go through a rabbit rescue. They have already-fixed rabbits and will allow one to pre-screen for potential compatibility. If one potential doesn't work out, they will allow an exchange. (In the UK, some rescues will actually do the bonding for you.) This can be a good option to increase the chances of winding up with a compatible match.
I'm not wanting to be johnny raincloud, but I do want you to be aware of potential outcomes and other options. Since you just got the gal today, perhaps you'll want to consider returning her -- if that is something you decide might be a better option. Food for thought.