Since you've mentioned Douglas lake...
presumably that's the one in TN near Gatlinburg/Sieverville Yes, it's in Dandridge.
There's currently multiple listings for 3+ acres for $199 - $250k, but these have been on the market for over 170 days which indicates that the price is over the market clearing level. You mentioned it's 8 ac but only 2 ac usable, so obviously it's on the water. Yes, it's on the water.
Does it have its own slip, thus making it more valuable for boat owners, or is it bare land? It had a dock at one time but nothing now.
Has there been changes in zoning such that 2 ac isn't able to be built upon and that larger acreage is needed? Same thing with septic.... are permits still available or have more difficult restrictions been put in place? These questions have a direct impact on viability of any sale (as might be witnessed by the time-on-market of existing listings). I know that there's septic and electricity on it. It needs a well. The in-laws ran water from the neighbor for a trailer that sits on the property, which is very old now with no value that I can see.
BTW, you never mentioned how far other the other two siblings are from the property in question; while you might be close if they are in, say TX, it's unreasonable for you to continue to require for them to keep interest in the property. We're all about 8 hours away. 2 in Michigan and 1 in SC. The in-laws used to spend time there in the spring and fall to extend the better weather vs Michigan
My experience: once last parent passed, the small house was put into a trust and used as rental. The house was across the country (>2000 miles) from two of us; had it been just land there would have been absolutely no reason to keep... it would have been sold, period. The continued K-1s causing tax filing delays, along with me recognising the likely upcoming costs (roof & HVAC) that would been expected and that would make the property either not give any yield or even require outlay to keep up, made me agree with the other to buy us out of the property. While others may have had some attachment to it.... I didn't (and the others in your case might not either. Memories, yes-- attachment, NO)