You can still use Survey123 for the questions just use collector for the spatial side. But if it is just a few you can do it in collector.
I had 175 tablet users with an avg age of 60 with many never seeing a smartphone before. They picked it up quick if you just showed them. Worth a test since it does not take long to build.
Full esri post on it is here https://community.esri.com/groups/survey123/blog/2016/07/30/understanding-survey123s-custom-url-sche...
My workflow is this
Create the form and publish.
Download the form feature service as a gdb.
Create a new GDB in catalog - this holds your collector features.
Add the FS that collector is going to use (point, line, whatever).
Add a key field to the collector class then pass this value to Survey123 (like you have been doing).
Copy the Survey123 FC you downloaded into the collector gdb.
Create a Relationship class from the Collector FC to the Survey123 FC.
Publish this gdb as a service.
Go into the Survey123 form and set the submission_url to the new HFS you just published.
Republish the form.
Now you can add the collector service to a map and all the relationship classes come along. Now you have your collector features connected to your forms. Forms to lines or polygons or whatever does not matter.
I have this working with 9 forms/9 relationships classes and works great. I can list all the forms for a feature or open a form and backtrack to the feature. Plus if you export the HFS to a GDB all the relationships classes come with it. They also works in ArcMap when connecting to the HFS directly. Oh and you can even see the linked forms in Collector - even other peoples forms!
Also what I did was add a field called XForm and put the item id in that field. Then in the collector map I can use that field to construct the URL. It then launches and prefills in the "Key" field you decided to use. This way you can actually mix and match forms if you want. Say 2017 features link to the 2017 form but the 2018 features link to the 2018 form.
Hope that makes sense and helps you.