Apologies in advance for using layman's language - I'm not a lawyer.

Over the past couple years I've been having more and more conversations with my dad around estate planning. We have a good relationship and I can obviously talk to him about this stuff but as I try to incorporate a future inheritance into my own retirement planning (and ask about it on different personal finance forums) I get a lot of pushback from the crowd. Which, fair. I get it. But some of the stories are these wild tales about poor old dad who starts to lose his marbles and marries a 23 year old stripper after mom passes away and she inherits everything.

I'm not here to debate whether and how to count chickens before they hatch, but rather the level of protection these SLAT trusts provide.

My parents are both 70, in good health, and have worked with an estate attorney to create SLAT trusts for one another (presumably in such a way that they don't run afoul of the reciprocal trust doctrine). I don't have the sheet in front of me but I think each trust has a couple million of room left under the lifetime gift tax exemption and the plan is to top them off by the end of next year. I have two siblings and we three are the secondary beneficiaries on both trusts.

Question: besides the risk of the assets within the trust losing value or the initial beneficiary spending it all, how much should one worry about the proverbial "remaining spouse remarries to a conman and gets talked into leaving them all their assets"? I haven't spoken to an attorney about any of this and as I said I'm not an attorney or estate planner. It also feels a bit weird to ask my dad about the nuances of such a sad hypothetical - he may or may not know and I'm not actually worried about any of it happening so I feel like raising the question gives it more weight than it deserves.

That said, for my own planning purposes, are SLATs pretty ironclad to protect against this sort of thing? or is there a fair bit of wiggle room? My siblings and I are all very close and get along well. I understand family deaths and estate issues can bring out the worst in people but I'm optimistic that won't be a problem for us (in other words, I don't expect a sibling to sue to change something).