Where do I go for free youth if I purchased online tickets to Paris museums for adults?

At most places they walk in with you, exception that o know of was Invalids, you have to get them a free ticket there, but i have been there 3 times now, all during busy summer season, and there is no long line there, which is surprising as its a great museum my kids actually enjoyed.

Note, i would not recommend you prepurchasing tickets. Itss usually nothing but hassle as you have to go and exchange the online vouchers . Have you looked at getting a Museum Pass, they can be great value and you can pick it up in paris or at airport when you arrive.

I think the Paris Museum pass is more $. Per person it will be $38 for us to see the Louve, d'Orsay, and de l' Orangerie. The least expensive pass I saw was $72 a person for 2 days. We cannot go on two consecutive days.

Paris Museum Pass per person :
48€ 2 days
62€ 4 days
74€ 6 days
Were you possibly pricing a "Paris Pass" or another "pass" that includes other extraneous stuff?

I'm not sure. It must have been another pass. If the two day pass is purchased. Does it have to be two consecutive days? For some reason, I am remembering you do. Can this be purchased in the train stations or in the city? We will be arriving by Eurostar train.

On our last visit, our hotel had a vending machine selling the Paris Museum Pass. We purchased from there since it was very convenient.

yes.. the Paris Museum pass has to be used on two consecutive days.. with all you are seeing I can't see the cost being 38 dollars.. do you mean euros?
Oh.. just reread your post.. you can NOT do two consecutive days well then a pass is not going to work.
I still would not pre purchase a ticket for the Louvre.. its absolutely not necessary and adds a step ( getting voucher redeemed) .. its easy and fast to buy your ticket at the many many ticket machines.. and as we all know the line for security is unskippable.
I enter via the Caroseul Mall .. its off of the Rue Du Rivoli.. then you skip the bottle neck at the Pyramid entrance.

The only way to skip the lines is to book a tour online? Many other countries you can purchase tickets online and then skip the line for will call which is much faster.

Yes, I mean Euros, not dollars. That right a 2 day pass doesn't work for us since we cannot go on two consecutive days.

We are staying in an apartment, so we will not have a hotel/concierge.