The best price for London to Paris is (per person) 171 € 2nd class or 184 € 1st class. A mandatory reservation with a railpass is 30 € 2nd class or 38 € 1st class.

A price for Paris to to Milano would be 138 € 2nd class or 158 € 1st class at 14.48 from Paris (arrives 23.10). A mandatory reservation with a railpass is 31 € 2nd class or 45 € 1st class.

The 14.48 from Paris is normally a direct TGV, but because of a landslide there is a (organised) bus transfer in between. It’s still considered a direct connection.

A railpass is 255 € 2nd class and 323 € 1st class. You need to add the mandatory reservations then, so it’s not cheaper than regular tickets. But you do get 4 travel days and you may do another trip. There's also not a great difference. 

There are other possibilities that are not faster than this where you need to change trains at least once (but without bus transfer in between and maybe to a more preferred time earlier in the morning, e,g. 8.18 from Paris, change in Genf (Switzerland), arrives Milano 17.40. This does cost (at the moment 149 € 2nd class / 220 € 1st class) for regular tickets. 

Thank you so much. 
We will likely take your advice and purchase the pass to allow us the opportunity for additional travel. 
I am unable to find the place to purchase the mandatory reservation however. It keeps trying to sell me a single ride ticket instead. 
I am obviously doing something incorrect. 
Your assistance once again would be appreciated. 

How many places do you need? Which class? And where are you trying to book?

When searching for two persons it does show availability from London to Paris for two persons at:

11.31

13.31 (just first class)

14.31

15.31

16.01

17.04 (just first class)

19.01

20.01 (just first class)

Here’s a link to do a reservation for London to Paris (might not work on a smartphone):

London to Paris (raileurope.com)

If the link does work correctly, it should show prices for February 25th in CA$ for a first class railpass (you need to change to the correct number of persons). If that doesn’t match or isn’t shown you need to change the settings. But verify what is shown before buying anything.

There’s a quota for passholder reservations so it should be booked soon. 

The correct price for this is 30 € 2nd class (CA$ 45) or 38 € 1st class (CA$ 56) per person (pay attention to buy the right class for your railpass chosen; first class comes with food and drinks on this route). 

For Paris to Milano, you need to decide which route to go.

I got them both purchased. 
 

Your assistance was invaluable. Thank you again!