“Under the FAA, absent unmistakable evidence that the parties intended the contrary, it is the courts rather than arbitrators that must decide ‘gateway matters’ such as ... [w]hether an arbitration agreement is binding on a nonparty....” In re Weekley Homes, L.P., 180 S.W.3d 127, 130 (Tex.2005) (orig.proceeding). We do not believe the cited provisions constitute “unmistakable evidence” that the parties intended for an arbitrator to decide whether nonparties are bound by the arbitration agreement, particularly in light of established Texas law placing the initial burden of proving the existence of a valid arbitration agreement and claims within the scope of that agreement on the party seeking to compel arbitration. See J.M. Davidson, Inc. v. Webster, 128 S.W.3d 223, 227 (Tex.2003) (<HOLDING>); In re Oakwood Mobile Homes, Inc., 987 S.W.2d
holding that a party attempting to compel arbitration must first establish that the dispute in question falls within the scope of a valid arbitration agreement holding trial court must decide whether to compel arbitration of personal injury claim of party who was not signatory to arbitration agreement holding that once the party seeking to compel arbitration establishes the existence of an arbitration agreement and that the claims raised fall within the scope of that agreement the trial court must compel arbitration holding that a party seeking to compel arbitration must establish the existence of an arbitration agreement and show that the claims raised fall within the scope of that agreement recognizing that in reviewing ruling on motion to compel arbitration we first determine whether party seeking arbitration established existence of arbitration agreement