As Rolf says, you can still playback a previous recording, while recording a single channel, but without 2 lnb inputs (ie, 2 multiswitch outputs), there's no possible way you can get full SKy+ functionality:
Without a multiswitch upgrade, 2 possible solutions are:
1) Does the tv distribution also get freeview? If so, just split the incomming cable using a wideband 450-2900 Mhz "satellite splitter", used in reverse, and you can send the 2nd output (reversed, so marked as "input!") to a separate Freeview receiver, which will at least give you those particular channels twice over. (note, must be a METAL BLOCK sat splitter, with dc blocking on one port for sat reciever, the usual white plastic coax splitters will just dc short the SKY+ lnb input socket!).
2) Needs co-agreement with other residents. If 2 other people want only terrestrial tv, and no Sky satellite at all, then MAYBE they would agree to share a single multiswitch output, from which they can both get all terrestrial channels. In which case, there's then one spare multiswitch output, which you could feed to the 2nd lnb input. Note, everyone has to agree, including the managing agent/ landlord, you might anytime be asked to remove it, and you also have to somehow run a 2nd cable into your flat from multiswitch.
Also, as Rolf says, you can split the one i/c feed and send to both lnb inputs, but either one port is dc blocked, or if not the higher dc volts will "override", so if you can't specify which lnb input a recording is done from, there will still be problems!
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