Welcome, I'm new here too. If you want to try to cross the two varieties, go for it for fun. But breeding tomatoes to get a stable plant is not something you can do like this to get a new tomato in the first generation of the cross (your pollinated flowers' fruits' seeds.

When you breed a tomato like this from a hybrid and an open pollinated variety, you are usually looking to make something of a particular characteristic set. Because better boy is a hybrid, it won't breed true and you will get a motley crew of offspring exhibiting many traits which will not transfer the qualities of Better Boy, including the disease resistances. On the other hand the OP cherry will give another level of complexity when mixed in, giving you many different tomatoes. Since you will lose many of the good characteristics, you won't likely be happy with most of what you produce, but you will have tomato plants.

But ... if you have a lot of growing area, take good notes, and have a bunch of pathogens to inoculate your newly planted seeds from the cross, you can eliminate the plants that don't have the resistances you want (like using Round-up), and then you will need to grow the rest out and see about viability, yield, and finally taste and texture.

Now that you grew say 500 plants and ended up with one that was ok, but not really better than anything, you have to plant and select the best seeds in a similar fashion for several more generations, until your improved cultivar becomes stable ... that means it the seeds produce an open pollinated tomato you can count on being the same and definable.

Then you can pay $5000 and register it and sell it to get your money back ;-) if you have buyers who think it's great.

Otherwise, genetics like this is like playing the lottery. Maybe you'll get lucky, you never know ;-)

As to whether the cross is a good one, there are many criteria to judge that. But first, you need to ask what exactly you want to accomplish, otherwise it can be subjective, seat of the pants. But that can be great fun ... with benefits after years of dedication and obsession ;-) JMO

The link below will help you know how to make crosses and how long you need to make selections to get to a final stable selection. Start by looking at CULTURE in that link.

First, you have to have a goal.So what is your reason for wanting to cross Better Boy F1 with largeRed Cherry,which is OP. and note that small fruit is dominant to large fruit.

If you save the Seeds from Better Boy, the F2 seeds, and put out a lot of plants you probably won't get either of the parents back/

Let me use Big boy F1 as an example.One parent of that is Teddy Jones, a family OP heirloom from the midwest.I wanted to see if I could get it out, and at the time my mentor was Dr.Oved Shifriss who bred Big Boy F1. He said I could not get more than 80%of the TJ genes out/

Better Boy F1 also has one parent that is Teddy Jones and the analogy would be the same/

So first you need to have a goal, and with that goal in mind, then chose what parents might be the best to attain that goal.

Carolyn

Here is a link that might be useful: crossing/genetic segregation