You can do this quite easily with a single dataset and a single line if you get the dataset right.
I've mocked up a small sample of data using the following...
This assumes two tables, one with material use and another with maintenance days
DECLARE @t TABLE(DateStamp date, Amount int)
INSERT INTO @t VALUES
('2021-01-01', 10),
('2021-01-02', 11),
('2021-01-03', 12),
('2021-01-04', 14),
('2021-01-05', 16),
('2021-01-06', 18),
('2021-01-07', 20),
('2021-01-08', 21),
('2021-01-09', 22),
('2021-01-10', 23),
('2021-01-11', 24),
('2021-01-12', 25),
('2021-01-13', 26)
DECLARE @m TABLE(DateStamp date)
INSERT INTO @m VALUES
('2021-01-01'),
('2021-01-02'),
('2021-01-06'),
('2021-01-07')
SELECT t.*, CASE WHEN m.DateStamp IS NULL THEN 0 ELSE 1 END as Maintenance
FROM @t t
LEFT JOIN @m m on t.DateStamp = m.DateStamp
Using this as my dataset query I get the following data returned.
![enter image description here](https://i.stack.imgur.com/dFDzr.png)
Now all I did was add a line chart with amount as the value and datestamp as the category group.
I then clicked the series line and changed the following properties...
Color
=IIF(Fields!DateStamp.Value <= Today(), "Blue", "Red")
MarketType
=IIF(Fields!Maintenance.Value=1, "Diamond", Nothing)
... and finally set the maker size to 15pt for clarity in this example.
![enter image description here](https://i.stack.imgur.com/MIqxI.png)
This gave me the following output
![enter image description here](https://i.stack.imgur.com/PqlaD.png)