'A' Record for Dynamic Link vs Normal Hosted Website

we have a domain on AWS - that has a 'A' record linked to a particular alias. We are planning to use the same domain for dynamic links on firebase. Firebase has given us a couple of IP addresses which we want to add to our A records on AWS.

I have a couple of questions here :

1. How do we add two static IPs along with an alias in Simple Routing ? I know we can use multivalue answer record set for this but I have the next question on that front.
2. If we use multivalue answer record, how will we make sure that the request for normal website content is always routed to the alias in the first 'A' record and the one for dynamic link is always routed to the second 'A' record ? Please look at the image url below.

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