EuroRail and Swiss Rail Same trip

Asheville, You have already described the situation accurately. Italian long distance trains require a reservation, Swiss trains never, German long distance trains "recommended" but not needed. What is the question?
"How do I use the EurRail Austria-Poland pass for the Italian portion of the trip," - that must be a typo.
How do you use a pass? The pass should come with instructions, but if you have a pass in general, just get a reservation (if needed) and get on the train.

But, why did you buy passes? Why did you buy a pass covering Austria when you aren't going through Austria? Andy why did you buy Italian and Swiss passes when you are only going on one journey in each country. It would almost certainly have been cheaper to buy a normal ticket from Florence to Bacharach.

Thank you. Forgot to mention, Several days in Austria, Germany, Poland and Switzerland as well thus the three travel passes to accomadate the days in each country.

When you travel from Italy through Switzerland to Germany, we change trains in Basel Switzerland, and again in Frankfurt. When we cross the border, does the conductor ask for your new rail pass or does the EuRail pass get us all the way from Florence to the first stop in the next stop in Basel Switzerland then we use the Swiss Rail pass to get through Switzerland and into Germany?

exactly what passes did you get? Its still unclear.

We usually travel with a global pass. Sometimes when trains change conductors the new one will ask to see it and sometimes they will not. I think it is a function of whether or not the first conductor passes along that you are ticketed all the way through or not. or it is just random!

Just show the conductor the pass/passes for your journey. Don't forget to validate the passes before use and if they are for a specific # of travel days fill in the travel date before boarding or as soon as you board. I have never made a reservation for a German train. YMMV

each pass needs to be validated before use.

Passes (except for German passes only for Germany) are valid only within the countries named on the pass.

An Italian pass is valid to the border crossing - Chiasso or Domodossola. Heading north, a Swiss Pass is valid as far as Basel. And so on.

Of course, both French and Italian passes are useless on faster trains unless you pay extra for reservations - some of the reservations on French fast trains as rationed.

Asheville, The ticket inspector / conductor will check your ticket on each train. A pass is just a special type of ticket. It be a different on person on every train. They will expect to see a ticket (or pass) which is valid for the whole of your journey on that train.
For the trip from Florence to Basel, the dividing line between the two railways is (as Nigel says) at Chiasso or Domodossola, depending on which route you take. The Italian pass will be valid up to there, the Swiss pass from there.
The on-train crew sometimes changes there from an Italian to a Swiss one. You should have got a map or instructions with each pass showing where it is valid. The map for the Swiss pass is here: https://www.swisspasses.com/railpass/overviewmap_en.pdf
Basel is the junction station between the Swiss, German (and French) rail networks.

If your only train trip in Switzerland is from the Italian border to Basel, it would be much cheaper to have bought a normal ticket and not a pass. And, depending on how many trips you are taking, the same may apply for Italy and Germany. Did you cost up buying individual tickets?

I know that (for whatever reason) Americans think first of rail passes when they think of European trains. But you can buy individual tickets, and with advance purchase discounts, that's usually much cheaper. Of course, a pass does work best for some people, and it's particularly useful for Switzerland. On the other hand, even Rick (a fan of passes) points out that it's very hard to make an Italy pass pay off.

If you can tell us which train rides you are actually taking, we can help you figure out the cost of individual tickets. Unless you are taking trains like mad, you probably can not come close to making these passes pay off. Even if you lose some money returning the passes, it's highly likely that it's cheaper to do that and buy individual tickets. Remember that when you buy a ticket (as opposed to using a pass) any required reservation is included in the purchase.

We will be traveling 15 days in Switzerland and have Purchased the Swiss Travel Pass for this portion of the trip. We will be traveling in Italy for 10 days and Austria 5 days for a total of 15 days and have purchased the Austria - Italy EuRail pass for this portion of the trip. We will be traveling in Germany for 16 days and Poland for 3 days for a total of 19 days and have purchased the Germany - Poland EuRail pass for this portion of the trip.

You have answered my question about our trip from Italy through Switzerland and into Germany on one day and how we will use the three passes mentioned above for this day's travel. Another question, do we have to be in Germany or Poland to activate the German - Poland EuRail pass? Our first entrance into Germany will be this one day trip from Italy through Switzerland into Germany. Can it be activated while on board?
Thank you

You would activate the German pass in Italy before boarding. That way it is valid upon entering Germany.