Question: Graph of paraboloidal surfaces

How can I get the follow graph of paraboloidal surfaces (ξ=1,η=2) with the coordinate vectors ξ⁰ , η⁰ , φ⁰ as shown in the picture.

Realation between cartesian coordinates and paraboloidal :

x=1/2 (ξ² - η²), y=ξ η cos(φ), z=ξ η sin(φ)

I wrote the following code:

Student:-VectorCalculus

S1 := PositionVector([1/2*(-eta^2 + 1), eta*cos(phi), eta*sin(phi)], cartesian[x, y, z]):

LH := PlotPositionVector(S1, eta = -2 .. 0, phi = 0 .. 2*Pi, coordcurve = [eta = -2, tangent = true, binormal = true, vectornum = 1], scaling = constrained)

S2 := PositionVector([1/2*(xi^2 - 4), 2*xi*cos(phi), 2*xi*sin(phi)], cartesian[x, y, z]):

LG := PlotPositionVector(S2, xi = -1 .. 1, phi = 0 .. 2*Pi, coordcurve = [xi = 1, tangent = true, vectornum = 1], scaling = constrained)

And I got the two paraboloidal surfaces with the vectors separently.How can I get only one graph with these two surfaces as shown in the picture (with ξ=1, η=2) ?