Hi Ichigo;
I want to offer constructive criticism without being demotivating
These two trees are going to be difficult to turn into bonsai. I'm not saying impossible - but you have probably read several of the recent threads here about bonsai "return on investment" or how quickly you can create bonsai from different material. These tree will take a while, because they have not been prepared for bonsai development. Their roots will probably not be good, and they have tangled trunks without taper or branch structure. If you are interested in ficus bonsai, I might recommend you try a bonsai nursery in Florida for ficus pre-bonsai that already have many years advantage over these two trees.
That is all the bad news. The good news is that, being ficus, they are probably the single most forgiving tree to do massive overhaul work on. If you want to work with both trees, I would recommend you study pictures of great ficus bonsai that have tangled multiple trunks so that you can start to plan for the future of your trees. It is often helpful to have a photo right next to you when you work on a tree. When you repot, you will want to start spreading the roots out as flat as possible, eliminating any deep or thick tap roots, so that after several repottings (after several years), the tree will be in a broad, flat tray or pot that will help accelerate a flair at the base of the trunks. You need to work on developing the taper of the trunks, which will mean eliminating almost all of the branches and chosing a new single leader that will become the sole new apex. All other branches will probably need to be developed from scratch - but they should pop easily from the trunks once you have cut the other branches back hard.
The key to ficus is keeping them warm, humid and in bright sun. I can't kill ficus here in Southern California (I have several growing in my yard, in containers, etc) and conditions are not nearly as optimal as they are in Florida. My dog just chewed through a 3" ficus and it completely recovered and is busy healing over a scar from having half of its bark removed. I have completely defoliated ficus year after year with no noticeable bad side effects. Just don't try to force them into small pots too early - you need a lot of wild growth from them yet and putting them into small pots will slow them considerably. Consider a large growing tray or growing flat.
I would also recommend checking with local resources (clubs) in your area since I am sure they will be crawling with ficus enthusiasts. There are some nice resources at the
Bonsai Societies of Florida page, with some nice photos of ficus bonsai as well.
I hope this helps! By the way - it would be rare that someone would graft a ficus tree. They reproduce very easily via cuttings. I can't quite see where you think they might be grafted, but it may just be a wierd bump or hump in the growth of the tree, something quite common with ficus especially as they age.
