How to convert a string to lambda expression?

[WomanPro]

Hello anyone, I have big lambda expression with many lines in vb.net.
It runs perfectly for me and it returns a boolean

CoverLonely = FilteredFreeGts.Select(Function(b) New With {
                          .Position = b.Position,
                          .GtsInfo = GtsInfo_,
                          .ChckFrd = .GtsInfo.FrdIenum.AsEnumerable,
                          .FrdIenumOfIenum = GtsFltrdIenum.Select(Function(ChckN) New With
                          {.CrntFrd = ChckN.SelectMany(Function(elm) elm.FRd.Select(Function(elmk) elmk))}.
                          CrntFrd.Select(Function(CrntFrd) CrntFrd)),
                          .FrdElement = .GtsInfo.TargetPosition,
                          .RollInPositions = LonelyGtsInDngr.Select(Function(t) GtsInfo_.Rd.Select(Function(FrdS) FrdS = t.pos _
                          And FrdS > Dice And
                          b.Position.stack.Count = 1 And t.stack.Count = 1).Any(Function(r) r)),
                          .FreeSteps = b.FreeSteps}).
                          Where(Function(i) i.GtsInfo.FrdDblIenum.Select(Function(iss) iss.Select(Function(js) _
                          EmptyRdPoint2CrucialArea(js, Dice, True) = False _
                          And Backgammon.CheckFreePosPc(js)).Count = i.FreeSteps).Any And '	(i.ChckFrd.min >= QuartetLbound And i.ChckFrd.min <= QuartetUbound) And _
                          i.Position.pos = i.GtsInfo.FrdIenum.Max + Dice And
                          i.Position.stack.Count = 1 And i.Position.pos <> 0).Any

When I get true value I am getting the firstElement of this sequence with an if statement. So, instead of any at the end I use .FirstOrDefault.Position which runs perfectly too.
I thought instead of writing this big code two times because it is not very easy readable, to convert the lambda expression to string and execute it but I don't know how to do that.
It's very easy to make it a string and change the last peace from .any to .FirstOrDefault.Position or whatever I need, but lambda expressions are not strings. So, how can I do this conversion? Or is there any way of executing a lambda expression through a string and how? I searched on google but I didn't find anything about vb.net, I found for other programming languages but nothing can work for vb.net. Any help will be much appreciated. Thank you so much in advanced.