Sharepoint DataFormWebPart and ListFormWebPart validation SP2016

Question

I'd like to add some custom validation to custom NewForm for external list.
The default new item form has in the ZoneTemplate ListFormWebPart but if i add a new form in SPD2013 there is DataFormWebPart instead of ListFormWebPart in my customNewform.aspx.
My questions are:

1. Is there any possibility to add another ListFormWebPart for one list?
   • I tried to copy the code of ListFormWebPart from deafult NewForm.aspx and paste it to ZoneTemplate in CustomNewForm.aspx (replace the DataFormWebPart with ListFormWebPart)...but when i saved the changes the form in NewForm.aspx just disappeared and the copied code in CustomNewForm worked perfectly...can anybody explain me this behavior?
2. I can do some validation for ListFormWebPart when i place the script to PlaceHolderAdditionalPageHead which uses these methods
   • SPClientForms.ClientValidation.ValidationResult
   • RegisterValidator
   • registerClientValidator
   • SPClientTemplates.TemplateManager.RegisterTemplateOverrides

this script works but when i copy it into the customNewForm.aspx (DataFormWebPart) form i got the error like SPClientTemplates is not defined
Do you know any way to write a script which will work with these methods for DataFormWebPart or how to define SPClientTemplates for DataFormWebPart or is it even possible to define?

I have a custom javascript validation for DataFormWebPart using PreSaveAction() function which works as intended but im forced to find some way which will use sharepoint objects and methods...

validation script for ListFormWebPart:

var StreetValidator = function () {
        StreetValidator.prototype.Validate = function (value) {
            var isError = false;
            var errorMessage = "";
            var re = new RegExp('[^ ]+ [0-9\/]+');
            var reTest = re.exec(value);
            if(reTest==null){
                isError=true;
                errorMessage="Ulica neobsahuje na konci cislo";
            }

            return new SPClientForms.ClientValidation.ValidationResult(isError, errorMessage);
        };
    };

MethodStreetValidate = function (rCtx) {
        if (rCtx == null) return '';

        var formCtx = SPClientTemplates.Utility.GetFormContextForCurrentField(rCtx);

        var validators = new SPClientForms.ClientValidation.ValidatorSet();
        validators.RegisterValidator(new StreetValidator());
        formCtx.registerClientValidator(formCtx.fieldName, validators);

        return SPFieldText_Edit(rCtx); //default renderer for Text field
    };

    (function () {
        var CVOverrides = {};
        CVOverrides.Templates = {};
        CVOverrides.Templates.Fields = {
            'Street': {
                'NewForm': MethodStreetValidate,
                'EditForm': MethodStreetValidate
            }
        };

        SPClientTemplates.TemplateManager.RegisterTemplateOverrides(CVOverrides);
    })();