what is the measurement of the 2 scoops? You also might be able to get an idea of how many she’s actually eating if you pour the pellets into a measuring cup in the morning and then again the next morning before adding new pellets. Then you can slowly decrease the amount down to 1/2 cup over several weeks. It might work best to give her 1/4 cup twice a day, since she’s used to be fed twice a day.
How much does she weigh? My kids weigh between 5 – 6 lbs and they get 1/4 cup a day.

The other thing is that around 8 months is when you want to slowly transition from an alfalfa based to a timothy based pellets. Also, it’s time to transition from alfalfa to timothy hay, if you haven’t already.

The most important thing, as you mentioned is unlimited timothy hay (or other grass hay – brome, oat, orchard). I find if bunnies are getting a lot of pellets, they don’t munch enough hay – which really should be the biggest portion of their diet.

I’m not sure how many veggies a day she’s currently getting, but as adult it’s ok to feed 2 cups per day.

I know that alfalfa is fattening.  I’m wondering if you could mix some timothy & your regular pellets.  I have to do a blend of foods for my cats b/c I have a diabetic cat and a kitty w/ IBS. 

I do 1/2 cup of pellets for my buns in the morning and free hay 24/7.  I then do a huge bunny salad for dinner.  I delicious blend of some of their favorites.  They also get their special veggies every other, i.e. baby carrot for Jessi and broccoli floret for Leo.  They are little bunny piggies!  They also love craisins as special treats!  I did have to get them used to this food schedule.  That took about a mos.  Both were pellet buns w/ few veggies when I got them, so they really had to learn to eat their veggies.  Now that I have them on that schedule, I have to adhere to it as well.

Switching any kind of pellet brands etc. should be done very gradually with a small dilution of the original pellet.  Timothy pellets are actually much better for an older rabbit because they are not as fattening and do not contain so much calcium which can cause bladder and kidney stones. The amount of pellets you are feeding them both is a little too much.  What you want to do is supplement with a variety of veggies.  There are a few feeding charts available online and do vary a little.  This is the one I follow:

Here is a chart for your older bun from this web site:

https://binkybunny.com/Default.aspx?tabid=60

This is for your "young adult" bun that is 8 months old from the HRS:

http://www.rabbit.org/faq/sections/diet.html#young

You may want to split the pellets in 1/2 and feed 1/2 in the morning and 1/2 at night (I do). Gravehearted gave you a great tip about measuring out how much your bun is actually eating.

Here is a good article about timothy based and alfalfa based pellets:

http://www.wisconsinhrs.org/Articles/Pellet%20Types.htm

If your older bun is not overweight and is so sensitive and has not health problems then I think you are OK with remaining on the same pellet.  If you do decide to switch the pellets with your bun;

This is a 4 week process that I’ve taken from Oxbow:

Week 1: Mix 1/4 of new pellets with 3/4 of the food you usually feed

Week 2: Mix 1/2 of new pellets with 1/2 of "old" food

Week 3: Mix 3/4 of new pellets with 1/4 of "old" food

Week 4: Feed 100% of new food

ooh, if you’re only feeding her a 1/4 a cup a day now, I would not increase the amount. I really would recommend following the slow change schedule that Scarlet_Rose shared above. Your mini-rex should be ok if you do the slow change like that. I personally recommend oxbow pellets, since they’re very healthy.

I can’t imagine feeding all the animals different foods!  Phoebe is supposed to get the DM wet food.  But anytime that we feed any of the cats wet food, Phoebe sits back to let everyone it eat b/f she even goes for any.  So then we moved her into the bedroom to eat her wet food.  The cats aren’t allowed in the bedroom.  Well, she thought she was being punished so she’d hide under the chair and not eat!  I just couldn’t win w/ her.  So now everyone gets DM dry food, well except the bunnies!