does a will override leaving property through joint tenency

My father in law died of cancer in1994, he was married to a women 20 years younger than him. He put her name on items he wanted her to have backdwhen the marriage was strong. about 1.5 years before he died she wanted a divorce but shortly after he got sick with cancer and, she knew she stood to gain several hundreds of thousands of dollars and property. if she could just hold out til he died, she was also openly dating once he was sick the man that she had been dating move in a week after my father in law died, they were married shortly thereafter. there was a prenup stipulating no marriage for a certain timeframe or money forfitted. she stole the prenup out of secrurity deposit box in front of all his kids. He did have a will that he had my husband the executer of his estate keep inj the box that left everything to his kids even the stuff that he had put in joint tendency ther was also sound reasons that came from my father in law that she may have been trying to expediate his death. Does the will superseed the jointtendency due to the loss of affeection. She also has a lot of family heirlooms and pictures from before she joined then family she refuses to give back outof spite my husband is the exeuter of his estate but his death was so long ago that we don't know if it's too late to instate the will. is there a time limit that you have to present the will to the courts even in certain circumstances where you didn't know of the will or the pre nup. She got away with murder and a lot of money we are seeking a lawyer i jusxt want to know if we have a snowballs chance in hell of recapturing of our fathers belongings i'm goingn after all of it all money an property that she stole from him. do i have a chance we live in kansas please email me at sassie_staci@yahoo.com CALL OR REACH ME HOWEVER POSSIBLE.. THANK YOU STACI LEE