The easiest way to do this without a lot of custom code on your front end (which will have to change everytime there's a backend change)...would be to add a trigger to pull the coordinates out of the geography (or geometry) object. This gives you a permanently populated and updated XY field.
CREATE TRIGGER [dbo].[tigger]
ON [dbo].[feature class]
after INSERT,UPDATE NOT FOR REPLICATION
AS
BEGIN
SET NOCOUNT ON;
UPDATE p SET
SHAPE = CASE WHEN i.SHAPE IS NOT NULL
THEN p.SHAPE ELSE Geography::STPointFromText('POINT('
+ CAST(p.LON AS VARCHAR(20)) + ' '
+ CAST(p.LAT AS VARCHAR(20)) + ')', 4269) END,
LON = CASE WHEN p.SHAPE IS NULL THEN p.LON ELSE p.SHAPE.Long END,
LAT = CASE WHEN p.SHAPE IS NULL THEN p.LAT ELSE p.SHAPE.Lat END
FROM feature class
AS p
INNER JOIN
inserted AS i
ON i.globalid = p.globalid
;
END
