Acrobat Reader DC and old versions

For some time I have had both Acrobat Reader DC and Acrobat Standard 7.1.4 installed on my Windows 10 PC.  The latter came with a Fujitsu ScanSnap scanner I bought some years ago and I use it when managing scanned documents for some of the features that are not supported in Acrobat Reader.  Hoever I prefer to use an up-to-date version of Reader when viewing PDFs from the web.

Recently (possibly since the June update of Reader DC), my Acrobat 7.1.4 installation got partiallty deleted.

I tried un-installing and re-installing both prooducts, but I don't seem to be able to have them both installed at the same time anymore.  The Acobat Reader DC installer seems to insist on removing all previous versions of Acrobat Reader and Acrobat Standard, and refuses to install if I don't agree.

Is there any way to over-ride this?  I cannot manage without my Fujitsu Scanner and Acrobat 7.1.4, so if they can't co-exit I will have to remove Readert DC and use an aternative reader.

Thanks

John