In Walker v. Packer, 827 S.W.2d 833, 840 (Tex. 1992), the Court reaffirmed the principle that "an appeal will not be an adequate remedy where the party's ability to present a viable claim or defense at trial is vitiated or severely compromised by the trial court's discovery error." A refusal to enforce the appraisal process here will prevent the defendants from obtaining the independent valuations that could counter at least the plaintiffs' breach of contract claim. The Court concluded that the failure to order the appraisals will vitiate or severely compromise the defendants' defenses to those claims. id In Walker, we held that, in the discovery context, "an appeal will not be an adequate remedy where the party's ability to present a viable claim or defense at trial is vitiated or severely compromised by the trial court's discovery error." Walker, 827 S.W.2d at 843. Thus, whether the excluded discovery goes to the heart of the party's case so that appellate relief is inadequate is pertinent. See Walker, 827 S.W.2d at 843; Jampole v. Touchy, 673 S.W.2d 569, 576 (Tex. 1984). But, still, the relator must "establish the effective denial of a reasonable opportunity to develop the merits of his or her case, so that the trial would be a waste of judicial resources." Walker, 827 S.W.2d at 843. Otherwise, the relator has not shown that the trial court's error vitiated a viable claim or defense so that no adequate appellate remedy exists. Walker, 827 S.W.2d at 843.