Transfer function with ARX

Obtain a transfer function from historical data.

I have used this document as a guide: Identify Linear Models Using the Command Line. With 2 input variables I had no major problem. But my doubt is when I have 4 or more inputs for a single output.

My doubt is

1. Use a "delay_system = delayest(ze,2,4,0,20,640000)" % ¿Is the rigth form?

My code is:

%

Input1 = [VfFeed VfSOL VfVel VfFINO]; % 4 inputs

Input2 = [VfFeed2 VfSOL2 VfVel2 VfFINO2]; % 4 inputs

Ts = input(Ts);

ze = iddata(VfWeigth,Input1,Ts); % 1 output, 4 Inputs, Time

zv = iddata(VfWeigth2,Input2,Ts); % 1 output, 4 Inputs, Time

Ze1 = ze(1:1800);

Zv1 = zv(1:1800);

delay_system = delayest(ze,2,4,0,20,640000) %

%delay_system = nk1 nk2 nk3 nk4

NN1 = struc(na1,nb1,nk1); % na1= 2:nk1; nb1 = 1:nk1; nk1 %

ARX_model1 = selstruc(arxstruc(ze(:,:,1),zv(:,:,1),NN1))

NN2 = struc(na2,nb2,nk2); % na2= 1:nk2; nb2 = 1:nk2; nk2 %

ARX_model2 = selstruc(arxstruc(ze(:,:,2),zv(:,:,2),NN2))

NN3 = struc(na3,nb3,nk3); % na3= 2:nk3; nb3 = 1:nk3; nk3 %

ARX_model3 = selstruc(arxstruc(ze(:,:,3),zv(:,:,3),NN3))

NN4 = struc(na4,nb4,nk4); % na4= 1:nk4; nb4 = 1:nk4; nk4 %

ARX_model4 = selstruc(arxstruc(ze(:,:,4),zv(:,:,4),NN4))