OK, Bob
Normally, the trick is to always have the primary source as the primary link in the chain. In other words, the item you use most of the time should be the one hooked directly to AV1. The secondary source should be looped through.
In your case it would be:
DVDR (Scart1)OUT--->Video SCART on Sky+;
Sky+ TV SCART ---> AV1 on Toshiba.
The switching feature is automatic. Whenever you are playing a disc on the DVDR, it sends a switching signal that will override the SKY+ signal - i.e. SKY+ will automatically switch into 'pass-through' mode, bypassing its own output, and feeding the signal from its VCR scart to AV1. This is a standard feature from the days of analogue broadcasting, and is one of the few unique beneifits of the Peritel Euroconnector (read 'Scart'). The good thing about this is that the pass-through should work even if you're recording a program on the SKY+, and want to watch a DVD on the Philips.
All this 'pass-thru' stuff means you'll need good quality cables to offset the (hopefully minor) signal degradation caused by daisy-chaining electronics.
Having said that, due to the nature of the connections on the 880 (Scart 1 RGB OUT, no IN & Scart 2 RGB IN, no OUT), you can't loop the recorder through the SKY box and record in RGB. For that, you MUST loop the output from the Sky+box through the DVDR, with the DVDR being the primary source. The only possible solution I could suggest is perhaps using the S-video output on the SKY+ box, (get an S-Video & 2 Phono TO Scart lead - Ixos or QED or even
el-cheapo brands like Vivianco make these) and having a secondary SKY+ connection to Scart 2 or3 on the TV. That way, when you're recording on the DVDR, you can still watch SKY in high quality (albeit not as high as RGB, but get a godd quality cable, and you'll see - S-video can be superb).
You could always just hook the DVDR itself to Scart 2 or 3 on the TV, and switch it to S-Video from its output (Scart 1), but you should always try to extract the best picture from high-resolution formats such as DVD. So, to summarise, I would recommend This:
SKY+ RGB OUT --->DVDR SCART 2
DVDR SCART 1---> Toshiba SCART1;
SKY+ S-video & 2 Phono Audio ---> Toshiba SCART 2 (or 3) via 'S-Video & Stereo Audio to SCART' cable
Long-winded, I know, but I hope it gives you something to work with.
All the Best,
Moory