Contests after probate

[dmatters]

I am the co-executor for my grandfather's will(myself and my husband). My grandfather has a small estate and we filed and recieved the documents from the court saying probate was complete. Now my 2 aunts want to contest the will- one on the basis that she requires additional funds thru the Family Relief Act (she is not a dependent) and the other aunt wants to file on the grounds of undue influence (she was named in the will to not recieve any of the estate). How long do they have to file their claims with the court, or can they even after probate? We, and the estate lawyer, would like to disburse of the inheritance to the rightful hiers as soon as all the claims against the estate are settled. I am not sure if we can do this until these 2 aunts have filed contests if they are going too. Do you have any advice?

 

[dmatters]

additional info

I forget, I live in Alberta, Canada. My grandfather had a will and he also left specific instructions that one aunt and her 3 sons (named them all) were not to get any of the estate, however, he did not say why he wished this to be so.
Any help you can give me about what grounds a person can have to contest after probate would be appreciated. As well, the 2 aunts in question were notified prior to the filing of probate that this was going to occur and they should seek legal advice. The 1 aunt is named as a beneficiary but wants more of the estate.