A Multi-cell dect would just not work properly if the antennas are to far apart from eachother.
A caller using a dect handset will experience a call drop when they walk to far away from the antenna.
During installation (or better, before) you should put your handset in "Survey or metering mode" and check the RSSI value (Received Signal Strength Indicator)
It should always be between -30dbm and -75dbm. You could stretch this a little bit, but keep in mind that (moving) people, pallets, machinery and so on can influence the signal strength.
If you don't want to take any risks, we can do the survey for you or with you.