Too make a long story short, basically the sister didn't check what supplies were available at the house where the party was to be held, so when the women with the decor showed up to set up there were no tables or chairs or even a place to put the food - which by the way only half of the order showed up because the caterer said that was all that the sister ordered.
Anyway, my point is that planning a shower involves a lot of logistics: a place to hold it, seating for all the guests, including tables, decor (can be as limited or as extensive as you want), entertainment/activities and food for your guests. It's obviously not as involved as a wedding is but whoever is hosting/planning a shower needs to make sure that the basics are available.
It's okay to delegate responsibilities to bridesmaids, moms and anyone else who offers to help but make sure that whoever is "in charge" is really overseeing all of the other tasks so that you don't have guests showing up with no place to sit.
I suggested that they could have thrown blankets or sheets on the floor and made it a picnic style party since the wedding will be outdoors on a farm, but the sister ended up driving by a garage sale a few blocks away on her way to the shower and after realizing they didn't have any place for guests to eat she drove back and picked up a table and chairs for the party.