Can you go back 10 years to question your grandpa's revocable trust. If it was transfer correctly? If not, then try to break the successors last will?

Impossible to say based on the few facts given, but the likelihood of undoing anything that far back is not very great. On the other hand, if the transfer was not in keeping with the Trust document, there might be a triable claim. As for challenging a Will, there must be some basis. The basis cannot be that you do not like it or think it unfair. Will contests based on flaws in the execution or the document are not very common unless the Will was not drafted by an attorney. Even if a Will is drafted by the person who signed it, if the basic testamentary formalities were followed, it will be honored. When a person does a Will, what they want and think is fair is all that matters, even if it does not sit well with people left behind. Will challenges must be based on some failure in the execution or intervening matter that calls into question whether the person who did the Will really intended what was done. Will challenges are commonly based on undue influence or incapacity (the lack of ability to understand).  Successful will challenges usually involve a person who is old, senile, suffering from dementia or memory loss or a person who is otherwise lacking in capacity to understand the significance of what is being done or is easily influenced and manipulated; and their is usually another person who has taken advantage of that lack of capacity or exerted dominance in some way to influence the person to do something that they might not have intended or did not fully understand.   Sometimes litigation over Wills involves the meaning of the Will. If the language is ambiguous and can be taken in more than way, a court may have to decided what is means based on all of the evidence presented. Will contests require litigation in court. There is only a window of time once the Will is filed and a probate estate is open to file a will contest. Will contests can be costly and take a lot of time, as evidence must be gathered, witnesses must be located, the case must be put together and presented to a judge in a trial. This answer is not intended to create an attorney/client relationship or to be taken as specific legal advice in response to your question. It is a very general answer based on general legal principals. Your only way of knowing whether there is any claim to be made regarding the Trust or the Will is to consult with an attorney who can consider all of the evidence you have and ask questions to determine whether you might have a case.