Just to be clear, do you use php56 only for the Ibay or for the whole server ?
If you use php56 (or php54,php55)
for the whole server, then you can use the AllowUrlfOpen per ibay with 'php_admin_flag allow_url_fopen on', because apache is the handler of php. You can add also specific values (MemoryLimit,UpMaxFileSize,PostMaxSize,MaxExecTime) per Ibay
If you use php56,php55,php54
per ibay, then you use php with a cgi application and you cannot add specific setting to apache with php_admin_flag or php_admin_value. Then if you want to add the setting AllowUrlfOpen you must use it for the whole php application by the command I gave.
It is the limitation I have with php-scl
In short
PHP SCL for the whole server -> all settings can be set per Ibay normally with db or with smeserver-webhosting
PHP SCL per Ibay -> all settings must be set in each php{54,55,56} properties
https://wiki.contribs.org/PHP_Software_Collections#Usage