I agree! Diet is very confusing. There are so many websites that say different things, it’s hard to know what is right and what is not… We recommend the guidelines thru House Rabbit Society.
You’re familiar with rabbits of course, so you know the most important part of their diet is hay, hay, and MORE HAY! Under 7 months old, they can get alfalfa hay, but since they are already 5 months, I would keep them on timothy hay (rather than switch and have to switch them back right away!) Unlimited, so as much as they eat in a day and then some… You can put some in their litterbox to help them use the box, and encourage them to munch while they do their business. Also, you can make a hay into a game… get a grass ball and stuff it with hay, fill a paper bag with hay, or sprinkle a few pellets underneath their hay so they have to dig for them. Any grass hay can be offered. Most people do timothy primarily, but Brome, Meadow, Orachard are all fine too. My buns get the Oxbow Orchard and Timothy hays mixed together and they love it!
After that, veggies are the next important part. They provide some fiber and help to hydrate their GI tract, and it’s closest to what their natural diet is. It’s recommended that each bun gets 2 cups of veggies per day, per 5 pounds of bunny. The best veggies tend to be the basic ones… dark green lettuces: romaine, endive, escarole, red-leaf, green-leaf. You can offer herbs: parsley, cilantro. Greens are a favorite of my bunnies and they are pretty inexepensive: mine especially love collard greens and dandelion greens. I only buy greens at the store, you ahve to be careful picking stuff from the yard as it may have pesticides or fertilizer on it. You should introduce each new veggie separately and offer it for a few days to see if they have a negative reaction to it.
Wet poops tend to be caused by too many pellets (or carbohydrates, sugars) rather than too many veggies. Like with the hay, timothy-based pellets are recommended after 7 months. If they are on alfalfa now, you can begin to slowly switch them over within the next couple months. At this point the pellets can be free-fed, but sometime between 7 months and a year, you want to get them down to no more than 1/4 cup a day. My buns share a 1/2 cup of pellets, they get them once a day, when those are gone, their pellet bowl is empty and they don’t get anymore until the next evening. As long as they have planty of hay, they won’t go hungry.
If they have always had an issue with runny poops, that can be a sign of a health problem too. When you take them in on Thursday, have the vet check their poops.
These are some great diet links:
Diet Info - BB
What Should I Feed My Bunny? - Dana Krempels, Ph.D.
FAQ: Diet - HRS
And an article about bunny poop, since it is something we are always concerned about… 
The Mystery of Rabbit Poop - Dana Krempels, Ph.D.