EasyBCD has been adding BCD entries for many years, and it works.
Even if you add an incorrect entry, that entry might not work, but nothing will be broken.
What else did you do ?
Had you read EasyBCD Basics
before using it if you're not familiar with dual booting ?
For the moment, if you've done something you shouldn't to break the boot with the advanced options, try Fixing the Windows Bootloader via the setup DVD
As long as you're using the latest version of EasyBCD, W10 is fully supported (to the extent that MS will allow - Some features of bootmgr are just not available on UEFI PCs, not a flaw in EasyBCD, but a MS restriction that cannot be circumvented)