Can they contest”? I suppose that means that you are asking about potentialities and that as of now the siblings have neither filed formal objections to the probate of their brother’s will nor started legal proceedings in an attempt to void your warranty deed.
Also I assume that since your husband is the sole beneficiary under the will he is also named as the personal representative and has already employed an attorney to represent him in probating the will. Which he should be doing with all haste!
Any unnecessary delay in getting that will filed and the administration under way will only give the siblings more time to marshal their forces and their dollars to pay an attorney to file objections to the will’s admission.
Regarding the warranty deed, I don’t see that the siblings would have any standing in court to move to strike the warranty deed - adequate grounds, within Indiana’s six year period of limitation, or not. Not unless they successfully contest the will throwing the estate into intestate distribution whereby they would benefit by having the deed voided.
We don’t know any of the circumstances surrounding the execution of the deed or the will. These are matters to be developed by your attorney. But I would think that where the friend retained a life estate interest and lived for 6years after your deed was made and delivered, the siblings wishing to have it voided on grounds of fraud or overreaching are going to have an insurmountable task in court.
And again, in my opinion they could not bring such a suit unless the probate court rejects the will. Plus a hell of lot more disgruntled family members threaten will challenges and much less every do it and even less succeed.
But you rely on the advice of your attorney.