Either combine picks, multiple picks for players or kick the can down the road.
Trade a first from this year for a future 1st plus an optional 2nd.
How often do we actually see this in the NBA? Such and such a team trades its first this year for a first and a second next year?
I don't know about trading a 1st for a 1st and a 2nd, but trading a current pick for a future pick(s) happens all the time, especially in the 2nd round.
Draft day 2015, Philly traded #35 for 2 future 2nds.
Draft day 2015, Charlotte traded #39 for a 2018 and 2019 2nd.
Draft day 2014, Memphis traded #35 for a 2016 2nd.
Draft day 2014, Atlanta traded #48 for a 2015 2nd.
Draft day 2013, Cleveland traded #31 for 2 future 2nds.
Draft day 2013, Atlanta traded #50 for a future 2nd.
Draft day 2013, Philly traded #43 for a 2014 2nd.
Draft day 2011, New Jersey traded #31 for for 2013 2nd.
Draft day 2011, Cleveland traded #32 for a 2013 and 2014 2nd.
Draft day 2011, Lakers traded #56 for a future 2nd.
Draft day 2010, OKC traded #18 (Bledsoe) for a future 1st.
Draft day 2010, Miami traded #50 for a 2013 2nd.
Draft day 2009, Minnesota traded #18 (Lawson) for a 2010 1st.
Draft day 2009, Miami traded #43 for a 2010 and 2012 2nd.
Danny can definitely kick the can down the road here, and for what it's worth, I don't think the Celtics currently have any 2018 2nd round picks.