Answer - Throughout their sixties success, the DC5 had set a goal of keeping things going to the far-off date of 1970. As American popularity began to fade in 1967, British popularity resurged, and so the decade of the sixties was filled with great success. But by 1970, the world had been toured, records had ceased charting, and life had other adventures to offer. The last DC5 single was "Here Comes Summer", mid-1970. The band broke up right around that time, though Dave and Mike still had a passion to do some more recording. There was also a contract to be kept with EMI, a 10-year deal that had begun in 1963. So Dave and Mike joined forces with three others: Eric Ford, Alan Parker and Madeleine Bell, forming "Dave Clark and Friends".
As to which recordings after "Here Comes Summer" were DC5 vs DC&Friends, it's impossible to be dogmatic. John Briggs describes the sorting process as a "minefield" in his message board post. I'm told by some "experts" that Dave Clark and Friends then recorded "More Good Old Rock And Roll", a maxi-single similiar to their 1969 recording. It was released as "The Dave Clark Five". . Then in December of 1970, they released a fantastic version of Neil Young's "Southern Man", again using the DCFIVE name. That same month, the album "If Somebody Loves You" came out, truly a collection of DC5 recordings, mostly their singles from 1969 and 1970. Then in July of 1971, DC& Friends released "Won't You Be My Lady", again attributing it to the DC5. Again, there is debate as to who truly recorded it. All three of these singles could have been by the original five, but from earlier recordings, we just don't know.
After that, they officially adopted the name "Dave Clark and Friends", releasing five more singles. None charted. The b-side of "Sweet City Woman" was actually an older DC5 recording, "Love Comes But Once". In September 1972, they put out the album "Dave Clark and Friends". It included three DCFive singles (Bring It On Home to Me, Paradise, and Put a Little Love In Your Heart), plus eleven other songs. There is some debate as to all eleven being DC&Friends or the original DC5. In the 1990s, when compilation CDs started coming out, the UK "Glad All Over Again" CD picked up two DC&Friends songs, ("MoreGORR"? and "Sha-Na"), still attributing the entire album to the Dave Clark Five. So there you have it. Just because a record label says "Dave Clark Five", it might be "Dave Clark & Friends", or vice-versa. Just because a record was released after mid-1970, doesn't guarantee it's not the DC5. Good luck.
The POST-BREAK-UP Discography:
Oct 1970 - More Good Old R&R / One Night / Loving You / Lawdy Miss Clawdy (dc5?)
Dec 1970 - Southern Man (dc5?) / If You Want To See Me Cry (dc5)
June 1971 - Won't You Be My Lady (dc5?) / Into Your Life (dc5?)
Oct 1971 - Draggin' the Line / One-Eyed, Blue-Suited, Gun-Totin' Man
Feb 1972 - Think of Me / Right Or Wrong
Jun 1972 - Rub It In / I'm Sorry Baby
Sept 1972 - DAVE CLARK & FRIENDS ALBUM (Southern Man / Bring It On Home to Me - dc5 / Signs / Won't You Be My Lady / The Time Has Come - dc5? / If You've Got a Little Love to Give / Officer McKirk / Paradise - dc5 / Draggin the Line / Think Of Me / One-Eyed, Blue-Suited, Gun-Totin' Man / Right Or Wrong / I Don't Know / Put a Little Love In Your Heart - dc5)
Mar 1973 - Sweet City Woman / Love Comes But Once (dc5)
Oct 1973 - Sha-Na-Na-Na / I Don't Know