Within your custom login control, you can just implement a "Forgot Password" link and redirect the user to your own custom SendPassword control, similar to this - https://github.com/dnnsof.../Login.ascx.cs#L109. Then for your custom SendPassword control, you would need to implement the desired custom logic similar to this - https://github.com/dnnsof...endPassword.ascx.cs.

Hi David, thanks for your answer!

We've already created a custom Authentication Provider, and we've just added the SendPassword.ascx classes for a custom SendPassword control to our solution.
However, if we try to navigate to our custom SendPassword control like:
url = this.navigationManager.NavigateURL("SendPasswordCustom", "returnurl=" + returnUrl);

Unfortunately, the custom SendPassword control doesn't render.
Is there something we've forgot to setup for this to work? Or do we have to declare our custom SendPassword control differently?

The components in our dnn file are declared like this:
<components>
    <component type="AuthenticationSystem">
        <authenticationService>
            <type>CustomAuthSystem</type>
            <settingsControlSrc>DesktopModules/AuthenticationProvider/Settings.ascx</settingsControlSrc>
            <loginControlSrc>DesktopModules/AuthenticationProvider/Login.ascx</loginControlSrc>
        </authenticationService>
    </component>
    <component type="Module">
        <desktopModule>
            <moduleName>AuthenticationProvider</moduleName>
            <folderName>AuthenticationProvider</folderName>
            <businessControllerClass>Modules.AuthenticationProvider.Components.FeatureController</businessControllerClass>
            <supportFeatures />
            <moduleDefinitions>
                <moduleDefinition>
                    <friendlyName>AuthenticationProvider</friendlyName>
                    <defaultCacheTime>0</defaultCacheTime>
                    <moduleControls>
                        <moduleControl>
                            <controlKey>SendPasswordCustom</controlKey>
                            <controlSrc>DesktopModules/AuthenticationProvider/SendPassword.ascx</controlSrc>
                            <supportsPartialRendering>False</supportsPartialRendering>
                            <controlTitle>Send Password Custom</controlTitle>
                            <controlType>Anonymous</controlType>
                            <iconFile />
                            <helpUrl />
                            <supportsPopUps>True</supportsPopUps>
                        </moduleControl>
                    </moduleControls>
                </moduleDefinition>
            </moduleDefinitions>
        </desktopModule>
    </component>
</components>

Hello:

I'm not sure about the real fix, at the moment, but the NavigateURL() method is designed to navigate someone to a view control.  Therefore, in a traditional module, you'd want to update the DNN manifest to switch Anonymous to View.  

Example:  <controlType>View</controlType>

But, you're creating an authentication system, so your control list should look more like this example.  (Note that it's not a module component.) 

Hi Will, thanks for the suggestion. As you can see in my previous post, we already have declared our Login.ascx file as a loginControlSrc.
If we want to create our custom PasswordReset.ascx and SendPassword.ascx pages, does that mean they should be included in a module? Instead of a package of the type: AuthenticationSystem?

Technically, as long as your custom authentication controls correctly navigate to and from the password reset control, you should be fine.  This is regardless of how it's implemented.