Tirano to Lucerne checked luggage

Hi
My 1st time on this forum so not sure it anyone has asked this question previously.

We are traveling from Tirano to Lucerne (same day) taking 1st the BE to St Moritz then regionals to Lucerne. Due to the number of train changes we wish to forward our luggage.

Another forum has told us that we are unable to use the "fast baggage" service from Tirano & can only use it from St Moritz. Problem is we do not arrive in St Moritz until 11am approx & the cut off time for fast baggage is 8am to ensure we would have our luggage same day.

Can we use just the normal checked baggage service from Tirano which would be checked in b4 8am & still be able to pick it up in Lucerne around 6pm that same day or will it as I am reading not be able to be collected until the next day

I have asked the question to Swiss Rail but the reply was not very informative

Hoping someone can help us

Many thx

Thank you Annika. Its not the space on the trains we are concerned with its the hauling a couple of large suitcases on & off so many changes. Our only other option is to pack a o/n bag with what we will need for 2days with out our luggage & Im sort of not wanting to do that so looks like taking them with us. Thank you again