Hello Linda, welcome to the forum and how exciting for you to be visiting the place where your relatives lived!
Reading your post I am not sure how long you plan to spend in Adelboden and whether you already have plans for the 16th and 17th. If you have some spare days there and don't need to leave straight away for Chur, on the 18th, I have a couple of suggestions for you. You can take a bus from Adelboden to Adelboden unter dem Birg then the cableway up to Engstligenalp where you will be able to enjoy a flat, peaceful round trail surrounded by mountains (you will hear marmots whistling though you are unlikely to actually see them). There will be goats and cows grazing and some pretty wild flowers and a choice of two places to enjoy a tasty lunch.
Adelboden doesn't have a railway station so for my other two suggestions you will need to take the bus to Frutigen to catch a train. You can take the train to Kandersteg where you can find the cable car to Oeschinensee. From the top station you walk down to the lake - there is an interesting sculpture trail there. You can return by the reverse route or, as we prefer, walk along the trail that follows the river down to Kandersteg.
Also from Frutigen you could take the train to Mulenen where you take the funicular railway up to the top of Niesen. There are great views from the top of Lake Thun and the city of Thun. If you are adventurous you can hike down to Mulenen.
If you have a day to spare in Chur, I would recommend the scenic train journey to Arosa. On a clear day it is worth taking the cable car from there up to Weisshorn, terrific views and a lovely restaurant. Back down in Arosa, there is the "squirrel trail" through the woods where the squirrels are not shy or afraid of humans.
To travel to Chur, if you can leave early you can take the bus to Frutigen, train to Brig and the Glacier Express to Chur. You will need to reserve seats on the GEX but you can follow the same route on regional trains, though it takes longer because there are train changes to make.
You can use the sbb timetable to research all the times of buses and trains. Be sure to put Andermatt as a via station on way to Chur or it will give the quicker route via Zurich.
Do you plan to use a rail pass? I would recommend the 8 day Swiss Travel Pass for convenience as it covers all your buses and trains and gives you 50% discount on cable cars and funicular or mountain railways. Arosa is included in Pass as is Glacier Express though not the reservation cost. Just board the trains and buses and show pass as requested by personnel. Show pass to buy discounted tickets for cable cars etc.
I hope I have been of some help and that you enjoy your stay in Switzerland