persistent fur balls

[StellaBella]

I am new here, and desperate. My 4 year old Maine Coon, has just had to have her 2nd operation in 6 months for lodged furballs in her intestines......they are quite large, about 3 inches.
I am trying to find out what is good to either, prevent large furballs or disperse them before they get too big. She is currently on Hills ZD feed which is for her problem with bowels, but has now settled down for the last 12/18months, and has been quite well in herself, she also has wet food, which shes does well on. My other cat, also MC, does not have problems, but his coat is quite silky as opposed to Bella which is quite dense. I brush her every day, and am now even thinking of having her shaved, especially around the belly which is very dense. So if there is anybody out there that has a similar problem, please help. As the vet said although it quite rare to have to operate to remove furballs, doing it once was bad, but now twice, and the likely of it happening again has increased, and if so, then we might have no option to put her to sleep, as she can't keep having operations. PLEASE HELP