Multiple custom login forms

@redwiper

You can replace the UM login shortcode with this shortcode:

[select_login_form member_form_id="385" user_form_id="3687"]

This code snippet will use one of the forms for login.

member_form_id if the URL has a member parameter like
https://domain.com/login/?member=true

and the user_form_id in all other cases.

add_shortcode( 'select_login_form', 'custom_select_login_form', 10, 2 );

function custom_select_login_form( $attrs, $content ) {

    $login_form_id = false;
    if ( isset( $_REQUEST['member'] ) && isset( $attrs['member_form_id'] )) {
        $login_form_id = sanitize_text_field( $attrs['member_form_id'] );
    } else {
        if ( isset( $attrs['user_form_id'] )) {
            $login_form_id = sanitize_text_field( $attrs['user_form_id'] );
        }
    }

    if ( ! empty( $login_form_id ) && is_numeric( $login_form_id )) {
        if ( version_compare( get_bloginfo( 'version' ), '5.4', '<' ) ) {
            echo do_shortcode( '[ultimatemember form_id="' . $login_form_id . '"/]' );
        } else {
            echo apply_shortcodes( '[ultimatemember form_id="' . $login_form_id . '"/]' );
        }
    }
}

Install the code snippet into your active theme’s functions.php file
or use the “Code Snippets” plugin.

https://wordpress.org/plugins/code-snippets/