In SQL Server can I insert multiple nodes into XML from a table?

SET @MyXml.modify('
      insert
         <myNode>
            {sql:variable("@MyVariable")}
         </myNode>
      into (/root[1]) ')

DECLARE  @NestedInput_SpecificDogNameId int
SET @NestedInput_SpecificDogNameId = 99
SELECT [dbo].[udfGetLowestLevelNestedNode_SpecificDogName]
(@NestedInput_SpecificDogNameId)

CREATE FUNCTION dbo.udfGetLowestLevelNestedNode_SpecificDogName
(
@NestedInput_SpecificDogNameId
)
    RETURNS XML
    AS
    BEGIN

    	-- Declare the return variable here
    	DECLARE @ResultVar XML

    	-- Add the T-SQL statements to compute the return value here
    	SET @ResultVar =
    		(
    		SELECT
    			  @SpecificDogNameId as "@SpecificDogNameId",
    			  t.DogName
    		FROM tblDogs t
    		FOR XML PATH('Dog')
    		)

    	-- Return the result of the function
    	RETURN @ResultVar

END

CREATE FUNCTION dbo.udfGetLowestLevelNestedNode_SpecificDogName
(
@NestedInput_SpecificDogNameId
)
    RETURNS XML
    AS
    BEGIN

    	-- Declare the return variable here
    	DECLARE @ResultVar XML

    	-- Add the T-SQL statements to compute the return value here
    	SET @ResultVar =
    		(
    		SELECT
    			  @SpecificDogNameId as "@SpecificDogNameId",
    			  t.DogName
    		FROM tblDogs t
    		FOR XML PATH('Dog')
    		)

    	-- Return the result of the function
    	RETURN @ResultVar

END

<Dog SpecificDogNameId=99>Astro</Dog>

CREATE FUNCTION [dbo].[udfGetDogCollectionNode]()
    RETURNS XML
    AS
    BEGIN

    	-- Declare the return variable here
    	DECLARE @ResultVar XML

    	-- Add the T-SQL statements to compute the return value here
    	SET @ResultVar =
    		(
    			SELECT
    			[dbo].[udfGetLowestLevelNestedNode_SpecificDogName]
    					(t.SpecificDogNameId)
    			FROM tblDogs t

    			FOR XML PATH('DogCollection') ELEMENTS
    		)
    	-- Return the result of the function
    	RETURN @ResultVar

END

SELECT [dbo].[udfGetDogCollectionNode]()

<DogCollection>
    <Dog SpecificDogNameId="88">Dino</Dog>
    <Dog SpecificDogNameId="99">Astro</Dog>
</DogCollection>

CREATE FUNCTION [dbo].[udfGetAnimalCollectionNode]()
RETURNS XML
AS
BEGIN

DECLARE @ResultVar XML

SET @ResultVar =
(
SELECT
dbo.udfGetDogCollectionNode(),
dbo.udfGetCatCollectionNode()
FOR XML PATH('AnimalCollection'), ELEMENTS XSINIL
)

RETURN @ResultVar

END

SELECT [dbo].[udfGetAnimalCollectionNode]()

<AnimalCollection>
  <DogCollection>
    <Dog SpecificDogNameId="88">Dino</Dog>
    <Dog SpecificDogNameId="99">Astro</Dog>
  </DogCollection>
  <CatCollection>
    <Cat SpecificCatNameId="11">Sylvester</Cat>
    <Cat SpecificCatNameId="22">Tom</Cat>
    <Cat SpecificCatNameId="33">Felix</Cat>
  </CatCollection>
</AnimalCollection>