Hi Loma2,
My guess is that IPFS doesn't allow for this at runtime. Why not just crate a secondary data source and concat the values together in a repeating node there. Then you can just use a plain dropdown to display the values. To create the concatenated values, you will need some way of repeating through the items. You could use code to do this or qRules insert with a counter - see Jo-Anne's latest blog on this.
Thanks!