Females are difficult to bond together, but it’s not impossible if you go about it the right way. They are more territorial than males due to a strong nesting instinct and they both should be spayed before proceeding. That will eliminate the hormones and make a bond more likely to work. Females can be spayed at about 6 months, that would be your first step.
This is my favorite bonding article: Love Match: A Guide to Bonding Your Rabbits - HRN
And some info on spaying:
Spay or Neuter My Rabbit? - Dana Krempels, Ph.D.
FAQ: Spaying and Neutering - HRS
I will also caution you to be careful, depending on where you got the bunny, it may have been missexed. This is common with petstore bunnies. It’s difficult to tell the sex of young rabbits, sometimes even for experienced rabbit people. If the 8 week old is a male instead of a female, he should be considered fertile within this next month. You may want to keep them separate JUST IN CASE, until you can get sex confirmation from a vet.