Checkout.liquid adding shipping info with javascript

Hello , as the subject line states, I’m looking for help with adding some custom inputs in the checkout.liquid template. The goal is to have shipping information on the order on the backend so that the store owner will know where to send a gift card but doesn’t want the customer to think that their preorder product will be shipped. I’m adding the fields with JavaScript during the customer information step of the checkout process. I have a checkbox that will also populate the required fields if checked. The data is being collected correctly on the front end, but when we click to the next step, I have a shopify rendered shipping form. Below is what I’m adding to the form. I have also include the error that I get on the next page as an image.

var input = `
                      
                        

                          ## 
                              shipping address
                          
                        

                    
                    
                        
                            

                              

                                

                                  

                                  

                                    
                                  

                                  
                                  

                                

                              

                              
                                
                                
                                
                                
                                
                                
                                
                                
                                
                                

                                  
                                  

                                    
                                  

                              

Enter a first name

                                  
                                  

                                    
                                  

                              

Enter a last name

                                  
                                  

                                      
                              
                                    

                                      
                                      Add a house number if you have one
                                    

                                  

                              

Enter an address

                                    
                                    

                                      
                                    

                              

                                  
                                  

                                    
                                  

                              

Enter a city

                                  
                                  

                                    
                                    

                                      
                                    

                                  

                              

Select a country/region

                                
                                
                                  
                                  
                                  
                              
                                  
                                  

                                    
                                    

                                      
                                    

                                  

                              

                                  
                                  

                                      
                                  

                              

Enter a ZIP / postal code

                                    
                                    

                                      
                                      

                                      
In case we need to contact you about your order

                                      

                                    

                              

                    
 
                        
 
                      

                      `;