@Lifesforloving1 I was in your situation, fairly recently, mum left entire estate to me, siblings came out with with every allegation going and them both being very wealthy, meant they could take it to court.
However, proving undue influence or the testator not having capacity is extremely difficult...
Undue influence? the main witness is dead.
Capacity? again, so long as on the specific day the solicitor was happy, then the fact they didn't have capacity the following day is irrelevant.... but a wise solicitor will consider capacity, so in my mums case referenced her memory, the reasons she was changing her will and made notes on her sound state of mind.
Only the High Court can hear a Will claim and your family will need at least 100k and if they lose, another 100k to pay your costs, none of these costs can come from the estate, which is another myth.
The block on probate will last 6 months, an individual cannot keep blocking it without good reason (evidence) as you can bring court action against them for doing this needlessly but what my family did was change who blocked probate, starting a new process... in the end, the costs of just using a solicitor was too great.
NWNF ? they can forget that, you might though.
My advice to you is ignore their demands until it goes legal and they start court action.... be very careful who you use, vast majority of solicitors are useless, some i spoke too didn't even understand the law... and have no idea how to defend High Court action, chose one with exp.
Of course all this depends on whether you ever want a relationship with your family, i and my siblings will never speak again, though even if i had changed the will, i think they would have still hated me.
Feel for you, its extremely stressful.